Buy it now, or else...
Buy it now, unless you want all the problems of a first-gen.
No, seriously, I mean this. I've been following Apple for quite some years now (since the Performa) and guess what? It turns out that the first gen, and mostly the second revision, has most technical issues for as far as I've seen in past history.
And remember: the new MacBook Pro will be more than a feature upgrade. To implement Intel's upcoming chipset, the motherboard will be redesigned (as I've read). Fit in a new screen? New case design? New ports?
Boy, I just ordered a Penryn since I never have trusted Apple on their early-adopters stuff. And thus far...it all packed out pretty well.
So choose: less chance of problems and faster than anything out there OR high chance of problems but get an even faster laptop which is still based on rumors?