I have never tried sour beer before, and was recently given a sour brown ale. At what temperature should I serve this type of beer?
Tough one to answer...
Since all sour ales have a very low pH, the sour flavor will be present no matter the serving temperature. With that in mind, the subtle notes of the beer will probably require the beer to be warmer than most beers when serving. I would recommend a cellar temperature, about 55F (12C) to bring out the best combination of flavor and drinkablity.
The best advice I've ever heard on sour beers is from the tour at New Belgium Brewery: Take a sip and think for a few seconds about what the beer is trying to tell you then take another sip. If the second was better than the first, take a third. If the third was better than the second then keep going.
Never be afraid to try new brews.