Mac iMac and Mac Mini: no new changes
at least until next year and given the economy probably not for quite a while. Apple has announced that it's desktop lineup is "set for the holiday season". They're not making any new upgraded or intros on the desktop line and they don't want consumers waiting them out.
So if you want an iMac or Mini....then just buy one.
Source: cnet.com's "applebyte" show.