Why would they wait then just to release an iMac speed bump in August/Sept when they could have done that last week at WWDC like they did with the regular MBPRo and MBAir? The Ivy Bridge desktop chips are available and have been for a while.
The ONLY sensible logic/reason for the iMAC to not have been updated at WWDC is that they are working on a Retina version of it.
I mean...releasing it when Lion is release and just with a speed bump...can't see Apple doing that at all.
Something else is going down..otherwise the iMac would have been released already.
What if they had extra inventory left over? They might want to wait a little longer no?