United Kingdom-based St. Peters Brewery added a gluten-free beer, G-Free, to its lineup in 2007. The brewery describes it as a "clean, crisp gluten-free ale with a pilsner lager-style finish." The brew is not in wide distribution in North America, but you may be able to find or order it through a specialty distributor.
Hambleton Ales, another British brewer, makes two gluten-free beers: its GFA and GFL ales. Again, these are not in wide distribution outside of the British Isles (where you can find them in many supermarkets), but you may be able to locate an importer.