If you use Google AdSense on your site or blog you may want to read some of the updates in their new policy. Jennifer over at jensense.com has written a pretty good article explaining the changes.

Removed was the specific reference to contextuall targeted ads. So the immediate assumption is that using other contextually targeted ads - whether IntelliTXT, Yahoo Publisher Network or another ad network - as long as the ads were formatted in a way that makes them appear different from other AdSense ads. However, there is a slight problem with this… the AdSense terms still prevent publishers from using other contextually targeted ads on a page with AdSense on it too.

http://www.jensense.com/archives/2007/01/what_does_the_r.html