I asked myself this question and had the assistance of several fellow nerds to help me out (hardcore nerds too, this kid's pleat chain-mail in his spare time).
Beers is CORRECT. But, only if you're referring to the individual containers. A beer is a can, bottle, glass, or what-have-you filled with beer. It's a (SERVING) of beer. A helping, if you will. But if you say "I want beer," you're not specifying a single serving. You're referring to all beer, an unspecified, vast amount of this one specific substance; beer. To say "man I had so much beer last night" is to say that you tapped the near-infinite resource that is beer, and you did so with an unquenchable vengeance. But to say "Man I had so many beers last night" is equally correct, you're just specifying that your consumption was meted into appropriate servings, just that you had a lot of those appropriate servings.
Personally, I don't like to refer to them as 'beers'. I think the problem is that people automatically associate homophones with each other grammatically. "Deer" is both plural and singular, so it stands to reason for most that "Beer" should behave similarly. Except, deer don't come on tap, and there're specific parts of deer that, when separated, can't be identified as just 'deer' anymore.
