Instead of Adsense (can't iframe) I've setup a affiliate banner rotator. Example Demo and source inside...

[Brandon Donnelson]

Since I can't stick Adsense in an iframe, I've been trying out Plan B, affiliate banner rotator inside an [iframe] with serialized loading so you don't get the same banner each time. 

Souce & demo and More on the wiki (in action here)-  http://code.google.com/p/gwt-examples/wiki/DemoAdvertisingAffiliate

Demo - http://affadpublish.appspot.com/adpublish - refresh to see the serialized loading

Brandon Donnelson

If I can do it, I'm sure you can do it 10x better :)

http://gwt-examples.googlecode.com