Haha gutsy! Total genius or utter fool move.
It would be completely foolish. During the run up to the WWDC there's going to be umpteen rumours of Mac Mini Laptops, Tablets, the "amazing" features of the iPhone 3.0, etc.
The Pre launch would be news for a day, but the WWDC keynote and any new products (and associated hype) would mean everyone would forget it. There's also umpteen zillion devs in San Francisco, all talking about the GSM iPhone.
(GSM matters because it will be hard to switch over from AT+T to Sprint. Palm would have to sell or give away "unlocked" Palm Pre's to developers)
It also means that Palm would be trying to position the Pre as a competitor to the Iphone. Its an 8gb CDMA "fun" smartphone with a (probably) low price point. The iPhone 3.0 will be 32 Gb, an established App base, and much higher price point.