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