It depends. Do you need one now?
If you don't need one, and just want one, then I'd suggest holding off. If the new revision doesn't impress you, the refurb still will get you a nice discount for your wait!
It doesn't look like you'll be missing out on anything major at this time. A faster FSB (800 to 1033, I believe), a bit of a faster processor, and a graphics card update are all given. Forseeable upgrades are the LED screen, multi-touch, and the keyboard lighting - but these may not come this update. If anything else comes, it'll be a huge announcement by Apple because it will be something brand new.