Normally AdWords and AdSense coordinate efforts to alert advertisers and publishers when there will be mainenance on the control panel. I noticed AdWords posted a maintenance alert on their blog a couple days ago.
Please plan ahead
Just in case you were planning to work on your campaigns this weekend, please note that on Friday, January 27th, the AdWords system will be temporarily unavailable from approximately 8 p.m. to 2 a.m. PST due to system maintenance. While you won’t be able to log in during this time, your campaigns will continue to run as normal.
As always, we apologize for any inconvenience this may cause.
As publishers soon discovered, AdSense control panel also went down for maintenance at the same time. The login page was unavailable to most publishers. I did manage to access my control panel, but when I clicked another tab in it, I was greeted with a note saying it was unavailable for system maintenance.
All ads are being served as usual, however.
Often, when both AdSense and AdWords go down for maintenance together, there is something new and shiny for publishers to play with. Hopefully we will see something new once the maintenance is complete.