The estimable 21st Amendment, based in San Francisco, is building community one tweet at a time, with the release of the first “Twitter-brewed” beer. It’s a nod to their SoMa neighbors, Twitter, the privately held company which is celebrating its third anniversary this month, as well as an experiment in social marketing of craft beer. Brewer Shaun O’Sullivan was profiled by the SFGate writer Jon Bonne, and expect a launch party for Spring Tweet on April 6, 2009.

I’m going to miss Spring Tweet, but did get to enjoy a glass of Watermelon Wheat (shown with the fresh wedge of fruit) last fall…