The tracking script is definitely working, and I'm using a couple of different trackers in addition to Google Analytics. They're all showing the same thing. Also, our ad revenue is down.
We did get hit by Panda in 2011. I wasn't sure this was the same thing because our rankings still look good.
We might be down a little more in Europe than in the US, but we don't have a lot of European traffic anyway, so it's hard to tell.