For everyone that is clamoring for a new iMac, what is it you think this new one will do for that the current one can't, even more so the iMacs from the last 3 to 4 years?
Be significantly less "glossy" screens. That is one of the major top 5 complaints over the last 4-5 years after Apple got rid of matte screens. I don't think they are coming back with a matte screen, but if elminate the gap between the glass and the LCD panel reflections will be somewhat less pronounced.
It will be substantively faster than the iMacs from 3-4 years ago also. Likewise graphics on par with Mac Pro from 2009 era also on the higher end models.