If Apple bumped WWDC to August it's Leopard & Pro Tower news
I think that we'll see a strong presentation on Leopard at WWDC in August, most likely highlighting native-Intel code enhancements AND 64bit "swaths" of code throughout. And in conjunction with that, Steve will announce a release date - my guess is MWSF '07 - which will put it even with the latest "fantasy" news from Microsoft on LongBore's public release. Steve will want to use WWDC to point out the real & vaporware differences between what will be in Leopard versus what was last promised for Windows "Vestage".
Also, the August WWDC will allow Steve to announce the launch of a MBP model or two with Merom - I see them keeping Yonah in some MBP models through the end of '06 - and he will announce the new Pro desktops (whatever their monikor). They will be available for ordering that day, but won't begin shipping in volume until the first weeks of September (same for a Merom MBP).
Alongside the new Pro tower(s) will be redesigned Cinema Displays, that all feature built-in iSight cameras (is HD-quality possible in the iSight of the "flagship" display?), and all will be HD resolution. The 17" may (likely) be replaced by a 19-20" at the low-end, followed by 23-25" mid-range and (my guess) is a larger 37" (or greater) at the high-end... Maybe the 30" flagship will remain, but at a $500 price-drop.
I know, I know, people don't see it happening until Adobe releases CS3 in 2007; but Apple already has their FCStudio as a Universal, and by WWDC I suspect several other pro-level apps from 3rd parties will be, too. And with a measureable performance increase via Conroe/Woodcrest, Apple may not be too concerned about launching new Pro machines a half-year before CS3.
As for the XServe; I can see that being upgraded to Woodcrest around Oct.-Nov. And I can see Apple making a "splashy" announcement at MWSF '07 that Viginia Tech has just upgraded their "Big Mac"(?) supercomputer cluster to Intel XServes.
I don't know; that's just my speculation on the subject.