I have experienced 100%, exactly the same thing. Noticed it first in late November. Took it to the dealer on 12/27 as it got progressively worse (more frequent). The kept it until they could experience the problem for themselves, which they did. They said they talked to Germany, and did some programming things to "fix" it. Got it back and for several days, no problems. Last week, however, it started again. Really bad now. I called the dealer and they said hold onto it while they are researching (has been a week now).
Curiously, how many miles do you guys have? I got my car in July 2007 and started noticing the problem initially at around 9,000 miles. Also, I live in Austin and didn't experience any problems until cold weather hit. Perhaps a simple coincidence, but curious is anyone else has experienced this?