I really like the Joel test, use it myself, and encourage my staff and interviewees to consider it carefully. However I don't think I can ever score more than 9 because a few points seem to contradict the Agile Manifesto, XP and TDD, which are the bedrocks of my world.
Specifically: the questions about schedule, specs, testers and quiet working conditions run counter to what we are trying to create and the values that we have adopted in being genuinely agile.
So my question is whether it possible for a true Agile shop to score 12?
On recommendation from an answerer below I am adding a link to my blog where I originally wrote about this and which led to me wanting to post the question here.
I'm putting this in because I agree with much of what has been said below and I wanted to declare my full position.