Not trying to be a nay-sayer, just being somewhat bold (against prevailing opinion/rumor). My predictions for WWDC:
1.) Apple will review the last year's accomplishments.
2.) Apple will discuss Snow Leopard.
3.) Apple will discuss the iPhone 3.0 OS and give a few demos of same.
4.) Apple will announce and demo some new iTunes App Store features.
5.) That is all folks...
Thus, there will be no introduction or demo of new hardware. No intro or demo of the 3rd generation iPhone (that will have to wait until Steve Jobs makes his return in another month or so). No new iPod touch (that will likely be seen this fall). No new Macs. No new Apple TV. And certainly no totally new products (tablet, netbook, etc.).
However, Apple will likely do some modest feature or price updates on the unibody MacBooks. Whether this happens today, or tomorrow, or sometime in the next few weeks I'm not certain.