Just “intalled” googles adsense on my page to see how it works. It was easy to install. Just fill in a form at their page, after a day they confirmed that my site was ok. I then just logged in to adsense and choosed how the banner was styled, copied the code into my template and then it was done. Now we will see how if anyone clicks that darn banner 
If you ever decide to start serving your XHTML as
application/xhtml+XML, you may want to read about my experiences with that and Google AdSense, which I’ve written about in Content negotiation, AdSense, and comments. In summary: it’s possible, but you need some workarounds.