Supernova IS........

.......Booster Gold. How did I guess?

"Superman being out of the picture is key.....one of two keys if you want to get cute about it."
Ralph Dibny telling Supernova this a few issues of 52 ago was what made me first suspect that Booster was Supernova. After all, there are no heroes that get Superman's goat like Booster Gold, as seen in Dan Jurgen's original Booster Gold ongoing series. The second key, which I didn't catch on to, was the Phantom Zone projector that Rip Hunter and Booster used, which Superman would have recognized in a heartbeat.

"Cassie, you said her name was?"
For Supernova to not know Wonder Girl, he needed to be on the fringe of the DCU.

"I can barely understand you when you're not linear!"
This was the clincher for me. This meant that Supernova wasn't that bright, which certainly matches Booster's description. This also eliminated Ray Palmer as a suspect.

And welcome back, Animal Man! We missed you, even though you were only dead for a week.

Or is Supernova.......

...Ray Palmer, The Atom? Preview pages seem to leave little doubt, but maybe Booster has his belt?

Who is Ronin of the New Avengers now?

Christ on a bicycle, Bendis......how stupid do you think we are? It's Captain America. Or MAYBE Hawkeye. Or MAYBE Daredevil. Or MAYBE Tony Stark......

Supernova..........

.....is Booster Gold. After last week's Penance reveal, I realized that I should have posted my prediction that the former Speedball would lose his shit after the events of Civil War. So, hope I'm right about Supernova, cause I want the bragging rights.