Logged in to Adsense today and saw the exclamation mark and freaked!! LOL, thought something had gone wrong at first, but what a great idea informing publishers in advance of system outages. Will hopefully stop a few of the threads being started on here about people not realising Adsense will be down for maintainance.
Never, ever underestimate the ability of DP visitors to freak out over any kind of system outage at Google .