Well, Captain America's dead. He's done been shot. Poor son of a bitch. What's wrong with you sick bastards? All Steve Rogers ever wanted was to express his love for this country by hitting people with a red, white and blue shield. And so he had to die? Damn you, America! Damn you to hell!
Actually, I've kind of got this feeling Cap won't stay dead. Call me crazy. I know that most comic book companies are too virtuous to cynically bump off a major character in order to sell some books and get some press only to bring him back a few months later. However, since Captain America spent the decades after World War II frozen in a block of ice until The Avengers found him, I'm gonna go ahead and say I don't think we've seen the last of him.
So how are they gonna do it? Allow me to float some theories:
It wasn't actually Cap that got shot. In today's topsy-turvy Marvel Universe, who can keep track of all the clones/evil twins/shapeshifters? Not me, that's for sure. It very well might have been someone who just looked like Cap. (And also changed their DNA to match his exactly.)
That wasn't a bullet. Hey, it might have been a high-velocity micro-sized suspended animation machine. In a world where a radioactive spider bite means super powers instead of a slow, painful death, are you really going to take a bullet at face value?
Super Soldier Serum saves the day! The dude is pumped full of a top-secret formula that makes him the ultimate soldier. Who's to say the Super Soldier Serum doesn't have some other funky side-effect like slowly healing bullet wounds after burial?
Tinkerbell Redux. What if a whole auditorium full of second graders clapped their hands real hard?
God Blesses America. Everyone knows that the Almighty loves this country. Does he really want us to be without our snazziest-dressed champion? I'm betting God will send Steve Rogers back to us so we can continue to be the best-loved country in Creation.
Unexplained Comic Book Circumstances. Could be Marvel doesn't even feel the need to explain themselves and Cap just shows up in the next issue of the Avengers and asks for a cup of coffee. That'd make just as much sense as anything else.