http://ps2.ign.com/articles/632/632447p1.html
I also got to play with the three new characters in a stage that no one had seen before, The Avengers' Mansion. Enclosed and less open than the older Daily Bugle stage, and packed with a ton of furniture and other things to be thrown around, this level definitely makes for confrontations reminiscent of old-school Power Stone 2 battles -- and it's good to see that a simple stage change can alter the gameplay experience so dramatically.
Of course, I took the Avengers Mansion opportunity to geek out and ask a couple of continuity questions like whether or not this was the "Pre-Disassembled" mansion or the current Young Avenger's wasteland, but the producer guys took it all in stride and confirmed that the storyline takes place before Wanda Maximoff went all House of M.
This storyline ties into the game's single-player feature too. To be shown in video form as part of a trailer loop at Comic-Con, "Story Mode" will be present a somewhat different experience than what most were probably expecting. You see, rather than just follow the Street Fighter model of tacking on an endgame movie after winning a couple of rounds with random characters, Marvel Nemesis tells its story via a full-fledged action game that comes complete with its own characters, stages, and settings that you won't be able to access otherwise.