Sounds like it has not been studied enough in detail to make any concrete conclusions about its effects...
This stood out to me: "Despite mainstream press alleging resveratrol's anti-aging effects, there is no accepted data to form a scientific basis for the application of these claims to mammals (see Life-Extension section below)."
Resveratrol is good stuff and works. The main problem with most of the products you buy is the form it's in. Seems resveratrol uptake is greatly enhanced when consumed with some alcohol instead of water. Last I heard there was a company working on a water based form that had enhanced uptake like when you normally would take capsules or tablets with water. Supposedly the absorption rate of resveratrol when taken with water is extremely low.