I would wait for it. The board is significantly smaller than the SR boards (Which Penryn uses), so up until now they haven't really had much to work with as far as a redesign.
Not that it matters, but DDR3 could be used in the MBP's, which would look nice on paper, even if it doesn't translate into an actual performance boost.
Nehalem is still where it's at, so if you don't NEED a computer soon, wait.
In fact, here is my current upgrade plan since everyone cares so much
Buy a Mac Mini when the new one comes out (Penryn, etc). Sell iMac G5 since I replaced it with a gaming PC back in May 2007. Dad takes my G4 to replace his G3. When the Nehalem Mac Pro comes out, I'll replace the Mini with that and give the mini to my dad. That's 2/3 computers updated, great. When the Nehalem MBP's come out, I'll give the gaming PC to my mom to run autoCAD, and replace it with a MBP.
Wait 8 years, repeat.