Don't get your hopes up. It is extremely doubtful that Apple will release new technology that is not available on the MacPro first.
This will be the order of updates over the next 8 months:
First, at the September 9th event, will be all the iCrap and software updates.
Second, will be Macbook Pros (and maybe Macbooks too) 2nd week of Oct.
Third, will be iMacs (around MWSF) with Mac Pro update announcements prior. A new computer platform will be revealed at this event!
Fourth, the Mac Pro will be redesigned in the spring when they use Nehalem. We will finally see new LED ACDs around this time.
Macbook Pros will get a total redesign around early summer.
The Mac mini is going to be replaced with a new computer platform at MWSF.
By this time next year, the major part of the line-up will be a lot different than it is today.