...now is the time. Here's the place.
Apple refurbs are some of the best in the industry, and I speak from experience. If I didn't have access to their educational pricing, I'd buy everything from them as a refurb. The savings are too good to pass up. If you want my advice, get the 4GB version for $399. I have an 8GB, and would prefer the $100 to the extra 4GB. Just don't forget the FatWallet Cash Back.
As indicated here, iPhone satisfaction rates are through the roof. I'm extremely happy with mine. It makes sitting in Midway Airport much less tedious, considering their lack of free Wi-Fi. If more sites start offering iPhone interfaces a la Facebook, it will be even better.