Yeah take a wait and see approach.
I personally have been flirting with the idea of getting a PSP (a used PSP-2000 off ebay from a high-rep seller most likely since that has homebrew, unlike the 3000 and unlike Go, you can play UMD games on it. Which is good for me since I have a rental subscription and you can find good bargains online on the retail UMD versions). But if a PSP2 is coming out soon, I know I would regret that decision. It's difficult for me to get excited about "last gen" hardware. It's not that "last gen" stuff is bad. I like to go back and play retro stuff every now and then. But let's face it, how many people here play with their previous gen stuff more than their current gen stuff? It's hard for me to be all that excited to play PS2, Original Xbox, Gamecube and GBA games when there's that constant distraction of current gen games coming out.
If the PSP2 is backwards compatible with PSP UMDs (I have the suspicion that Sony is going to abandon physical media completely and go DD-only with PSP2 as well though :(), even more reason to wait. Especially since the Go can't play UMDs (and not all PSP games are on PSN. Some are UMD-exclusive.)