Ellen Troyer and others had a nice conversation about resveratrol in the FitEyes.com mailing list. (I can post the whole conversation below if requested.)
I enjoyed reading this conversation. There are lots of good points here. However, for me, the single most important statement was the one below by Ellen.
Since resveratrol is only one of the nutrients found in grapes and wine, it makes biological sense that it would be the most effective when presented with a balanced amount of other polyphenols molecules.