A WebmasterWorld thread reports that Google AdSense was was down for about two or three hours this Saturday, February 10th. Reports are not geo-specific. They came from several places in the US, as well as overseas.
I would normally let this slide but still, some folks are reporting issues after they log in. Either error messages load up or nothing loads at all.
I personally just tried it and it seems to work for me.
Forum discussion at WebmasterWorld.
Update: AdSense Advisor confirmed the issue at the thread:
Any outage you experienced with the AdSense homepage this weekend was a minor site issue, not system maintenance. Sorry for any inconvenience this caused, and please rest assured that the issue didn't affect ad delivery or click and impression recording.I know it can be stressful to lose access to your reports unexpectedly, but don't worry - we'll keep letting you know about scheduled downtime in advance, both here and on the blog.
Thanks for bearing with us! -ASA