On Saturday, February 20th, 2010 the AdWords system will be unavailable from approximately 10AM to 2PM PST, for maintenance. While you won't be able to sign in to your accounts during this time, your campaigns will continue to run as usual.
AdWords system maintenance typically occurs on the second Saturday of each month from 10AM to 2PM.
We'll continue to update you via the blog as we always have, but please make note of the February 20th date and of our scheduled maintenance further down the road.