Everything was upgraded in the May iMacs except the screen resolutions, which are still the same as the new October iMacs.
The May iMacs are really nice. Apple Stores have some left over. Give them a call and see if one near you has one. They call them EOL (end of life). They have the 17" Combo for $999.
Really, the new iMacs (October) are only better if you need a remote (useless unless you are using it as a media center) and a built-in iSight.