Secret Identities

Watch any of the countless detective shows on television like CSI or Law and Order. It is not difficult to find someone in the information age. So how hard is it for a hero to maintain his secret identity?

Can someone get a picture of the heroes? Masks are probably not going to be very effective, and don't disguise height, build, or race. Add descriptions of prominent facial features, hair colour, voice and you've enough for a profile. Run it on TV and the heroes won't want to go outside. Maybe they search driver's license registrations too.
Also, one would assume the heroes need specialized services or goods. Gunfight between heroes and villains? The cops will start checking emergency rooms and clinics. Your costume got shot up? There has to be some place you'd get it fixed or replaced.

Even worse if the law gets a hold of any identity information: address, phone number, name. Now they can find your credit information, credit card purchases, phone calls, etc.
Then, there's simple detective work. Plot where the Crusader has been spotted. Maybe he lives somewhere in that area? 
Along more homeland security lines: recently they've tested software that matches face-shots from security cameras (ubiquitous nowadays) with mug-shots of known criminals.
In fact if you were to be completely realistic, I suspect your players would give up in frustration. So just choose some clever methods, allow the players to foil a few, and hand wave the rest away.
There aren't cameras everywhere but probably more than you think. Traffic lights, ATMs, stores, some apartment buildings. Then there are the ones that will be mounted on police helicopters, dashboards of patrol cars, etc. If you're really determined, you'll start plotting his activities and lying in wait where he's likely to be.

You can pretty much count on eventually figuring out someone's skin colour and maybe eye colour. Once you've got that, if he has a driver's license, all you need is time.
And forensics will tell you a lot. Blood and even sweat reveals a lot of information. It won't necessarily point you to the suspect, but it will let you identify him for sure once you have him. Triangulation is also your enemy. It would take between probably one and six months to figure out where a superhero is based if he hangs out mostly in one area.
Basically, short of some really weird cases (like being physically transformed such as with a Mystically Bestowed character) it's just about impossible to maintain a dual identity in the modern world.

That said, here are a few dodges you might take:
- Sympathetic Officials: If the Mayor, the Chief of Police, or some other major figure is secretly on the heroes' side, he can deflect some of the trouble they would get in. Files are "misplaced." DNA results are "inconclusive." The heroes have some measure of protection as long as they don't mess up too bad.
- Mission Impossible: Maybe the Paranormal Enforcement Bureau, or whatever isn't totally committed to shutting down supers. Maybe super terrorism and super crime is so epidemic that they (at least under the table) are recruiting them to act as deniable assets.
- Untraceable: This one's pretty hard, but if your group has the means to wreck detection methods they'll have some breathing room. You'd need someone who can disrupt electronics to knock out the surveillance cameras, someone who can "cloud men's minds" or some such to make sure any eye witnesses are unreliable, and some way to acquire medical care, fresh spandex, and whatever equipment they need under the table (which means they'll all be criminals).

Does it really matter what Captain Liberty thinks about the Red Demon if police refuse to investigate him, grand juries refuse to indict him, and judges will throw out cases against him on the slightest technicality?
Don't forget if the heroes create enough commotion, the press is going to get involved. Press helicopters following the heroes along on their attempt to escape make it even harder.
If they make the description public, then someone is going to call the police on their cell phone when they see him, or someone like him, in costume or out. Just another thing making the police's job easier. Somebody might even try to make a citizen's arrest creating a whole new dilemma for the hero. 

You might take the tack of The Fugitive: one elite group whose mission is to track down the supers. But they're a small group and there are numerous supers to hone in on, which means they have to carefully allocate their time and resources. So you ask yourself: are they going to go after the villains or the vigilantes first? Also, the government is going to want these supers as friendlies since there's this war of terrorism thing going on.

Or you might take the direction that the government is after these metas (because they can't control them), but there's another group of non metas who provide smoke and mirror cover for the good supers. They like having vigilantes out there to clean up the streets, etc. Maybe the metas know about this support group ... maybe they don't. 

A lot of supers also have super genius friends (or members). That means that, whatever technology one might use to film and identify supers can be thwarted. White noise generators that are powerful enough to affect cameras, ad nauseum. Maybe there's even one super intelligent hero who's made it his hobby to hide superheroes from information technology.
And finally, let the people who are playing the supers figure out how they're going to evade the law. If the law is a factor you're going to put into the game, then your players will need to know that up front and figure out how to deal with it. Just keep in mind: if you make the law too big brotherish (too large, too technological, too powerful) then you'll be in danger of sucking the life out of the hero side of the game.

Also, don't do dumb stuff. Your civilian identity should not be the person most identified with the hero. You should have people who can legitimately cover for you and you should have good excuses ready. Your Hero Identity should work in specific areas other than where he lives or specifically work to spread the busts out to avoid making a pattern. Only don the mask when needed, and do detective work in disguise, never in costume or in your mundane identity. Break into the police communication system.

Have a movement superpower that will allow you to elude helicopters and a dozen police cars at a time. Have a way to get to a home base that is not traceable. Take advantage of the unreliability of witnesses. Use decoys, simple disguises, and move quickly, quickly, quickly. Mouths are pretty distinctive, so either cover your mouth or wear lipstick.

There are certain things to keep in mind when dealing with Law enforcement;
The first is jurisdiction. City officials have far less resources than the average Federal agency. State agencies have a lot of resources, but even those have limits. Federal agents have access to a vast array of resources (though there are hierarchies in their departments) but there are priorities and pecking orders within each of these agencies. Are they just 'low level' FBI agents, X-files level or ultra secret director elite level?

The second is political. This is always a very complex thing, and can make the campaign interesting; indeed there could be a whole web here the characters do not even know about. For example; what is the ultimate motivation/ attitude of the local DA vs. Superheroes? What about the mayor? Are these separately elected positions? What about the governor? What about the President?

The third is practical. Noting the above two questions (which basically entails that if you're serious about this on a complicated level you should populate the city, state and local federal officials and their various attitudes)...what do the characters do? How many supers are there?
If there are at least a hundred masked crime fighters in every major city, the government simply won't have time to track them all down properly. It will focus on the flashy ones, the ones that cause the most property damage, and the ones that are the most likely to get them prestige in the news media (in that order). Flashy being easy to find (less work), property damage causing the most complaints, and prestige in the media equals more budget for their department.

If the hero's don't hang around and give interviews but disappear into the night, descriptions will be *very* bad ("He was 12 feet tall, sir!"). People get it wrong all the time. They might even finger the wrong dude ("The Crimson Avenger saved me!" when really it was the "Red Devil"). If a known, registered, trusted hero vouches for you, the authorities back off.