I reckon if we see anything at WWDC, it'll be an HD lcd option for the 17" (maybe 15" too, but I doubt it).
By my reckoning, the PB's are due for an update in about September, given that the updates have all been about 9 months apart (excluding the early intro of the 12" and 17" AlBooks). That suggests a Paris launch, and sure enough, google tells me that PAE is 20-24th September.
Given that it's still (only just!) April, I wouldn't expect any news or surprise releases before August, and I say go for it
