The higher the temp the faster the beer will age. Check out beeradvocate, they have listed many of the styles of beer and the recommended serving and storage temps. They have a whole forum section specifically on aging. In general the bigger the beer, the warmer the temp. Once I get my kegerator set-up, I will be aiming for a serving/cellar temp of 38*, a little cooler then what they recommend, but I am going for years. Also, temp consistency is a big key, I think this months BYO had an article on it, but swings in temp are far worse than storing at 50* as opposed to 40*.