Not today, but I've noticed a lot of problems over the last few days. I've gotten everything from "Internal Server Error" to a general "Try again later" error to "Connection refused" or "connection timed out." This seems to be happening with Adsense and, at times, with Adwords as well.
Maybe Google didn't anticipate such a big response to Adsense, and doesn't quite have the capacity to keep up? Hopefully, they're working on adding more power to the system.
It's pretty surprising, really. I've always considered Google to be extremely stable, but the last few weeks I've had to reevaluate that stance a bit.