The folks over in the AdSense team recently wrote up a good, relevant
blog post, "Behind the scenes of scheduled maintenance":
http://adsense.blogspot.com/2009/01/behind-scenes-of-scheduled-maintenance.html
It's written with Publishers rather than Advertisers as the intended
audience, but much of the information applies to the general AdWords
system during our monthly scheduled maintenances.
Also, while I'm on the topic of blogs, I wanted to make sure that our
AdWords API Google Group members were aware that there's an official
Google blog dedicated to the AdWords API:
http://adwordsapi.blogspot.com/
We cross-post all the big announcements to both the blog and Google
Group, but there are some tutorials and tidbits that are found only on
the blog.
Cheers,
-Jeff Posnick, AdWords API Team