I just saw this, if this is it it looks like we are getting a bump in graphics, the screen, and some hard drive space. Not really a big leap, its nice to finally know though..
http://reviews.cnet.com/desktops/apple-imac-24-inch/4505-3118_7-33541091.html?tag=TOCrightColumn.0
http://reviews.cnet.com/desktops/apple-imac-24-inch/4505-3118_7-33541091.html?tag=TOCrightColumn.0