Its not my area, so I don't know how easy it is to do, but I do think it could be a space for a third-party to step in. Someone figures out how to handle the twitter/payment side, reaches out to some local breweries/bars, takes a small cut of the money for each beer tweeted. Its not going to be a super profitable business, but it might be a fun sideproject for someone.
I forgot to add the 3rd benefit to the brewery is that I would assume, in general, when people stop in, they don't come alone, and they don't just have one beer and leave. Once they're in the door, they tend to spend more money.
