Silver City Brewing has made a Kellerbier that they will be rolling out at a private event at the brewery later this month. I just got a call from the brewer with an invite.
They will be serving the bier in earthenware steins. should be a fun night. I don't believe I've ever had the style.
Here's a brief description of the style from Beer Advocate
A rather old, rare, and unique German beer style, Kellerbiers are unfiltered and unpasteurized lagers that date back to at least the Middle Ages. The beer is matured, unbunged (beer is exposed), in deep vaults. The final product is a smooth, naturally cloudy beer that's rich in vitamins (from the yeast). Hop bitterness can be high and alcohol will vary. Zwickel Bier is similar to a Keller, but not as pronounced.