If there's a processor bump, there's USB 3.
At this point anything is better than nothing. Personally usb 3 is a big thing in my book future proofing the iMac for couple of years.
Future proofing came with Thunderbolt ( add a TB->USB3 ) adapter!
I can't come up with a reason that they would have waited until all of the 2012 GPUs are released and still just done a CPU jump. If they wanted to do just CPU they could have done that before WWDC.
I just hope we can get some sort of ssd options as that would improve performance SO much!
Except that USB is affordable. The cable alone for TB costs twice as much a USB 3.0 enclosure with cable.
For my money, I'd buy a TB enclosure before I would by a USB3 enclosure.
Future proofing came with Thunderbolt ( add a TB->USB3 ) adapter!