New Google Webmaster’s Guidelines
According to Matt Cutts, the FTC thinks you should clearly mark paid links. If you do clearly mark paid links Google editors will penalize you for buying / selling links, then they will pay an AdSense spammer to steal all your content. Don’t worry though, as Google doesn’t clearly mark their own ads.
Look at how closely timed the above posts were. Why would any webmaster mark their own sites to be penalized and stolen? Clear language is a wonderful thing.