Marin is a good brewery. I like several of their beers, and one of these days I will get around to visiting. I hear it's a nice little trip from SF.
Doug, it's Ten Commandments (aged in bourbon barrels), Gift of the Magi (aged in French oak barrels), and Serpent's Stout (aged in Port barrels).
Not sure where you stand on sour beers (I love them and really enjoyed the Stone Sour Fest last summer), but it definitely has some elements of that, along with stout characteristics. My all time favorite beer is Lost Abbey's Angels Share, which is aged in either bourbon or brandy barrels (depending on year), so I like that part of it for sure. But you really get an interesting mix with the Port in there.
I think it's kind of hard to explain, but you really know you're drinking something different.