Apparently, balloonhat and I aren't the only ones unsure who exactly we are looking at here. So, courtesy of MSN, here's the line-up:
Michael Fassbender stars as Magneto, Rose Byrne plays Dr. Moira MacTaggert, January Jones plays The White Queen Emma Frost, Jason Flemyng plays Azazel, Nicholas Hoult plays Beast, Lucas Till plays Havok, Zoe Kravitz plays Angel Salvadore, Jennifer Lawrence plays Mystique, James McAvoy stars as Professor Charles Xavier.
Hero Complex just ran a piece where one of their reporters visited the set. Here's some stills: