Neither of my two groups drinks.
When I'm DMing, I find that even one beer wrecks my concentration... and I need every advantage I can get!
When I'm playing, I'd be happy to have a beer or two over the course of the session, but past experience has made me a little hesitatant to open that door.
Previous groups I've been in that did crack beers during sessions got a little *too* casual for my tastes. I'd rather focus on the game and stick to coffee/coke
But if somebody else wanted to crack one or two I wouldn't have a major problem with it.