Don't expect much in the way of Mac Pro upgrades this year IMO...if you need an updated system now, buy one now.
I disagree. While me may not see the Stoakley-Seaburg, the Mac Pro has been stagnant since the last WWDC. The Quad core was a new option, not a hardware update that follows with current pricing.
Xeons are taking a huge slash this summer, I expect the Mac Pro to reflect that new pricing by shifting the CPUs, most likely phasing out the 2.0
My Predictions for WWDC:
CPUs shifted: 2.0 phased, more octo options possibly
RAM: 2GB base, unless they move to DDR3 (stoakley)
Video cards: New base card in the 8xxx series and new BTO options
HD: Maybe 500GB stock, probably not though
I think stoakley seaburg is an option, even though DDR3 will be expensive it really isn't much different than the FB-DIMM pricing when the Mac Pro was originally released.
Although I am not really sure as to whether or not Stoakley will use FB-DIMMs, I am assuming no, I couldn't find any stong data on it. I do remember a report saying Intel was dropping FB-DIMMs earlier this year.
Anyhow, wait until WWDC which is only a few days away.