Here's some great information on the taste influence of different oak in different kinds of wine, and how it adds structure, complexity, good and bad flavors, astringency, etc.
http://www.winebusiness.com/winemaking/webarticle.cfm?dataId=41530
Cheers,
Oskaar
http://www.winebusiness.com/winemaking/webarticle.cfm?dataId=41530
Cheers,
Oskaar