Part of a small beta test group trying out a new Google AdSense feature called general category blocking.
General category blocking lets you block ads that fall into predetermined categories. At this stage you can only opt out of a set number of categories. The feature is only availbale in the new AdSense interface.
First indications are that this filtering option will not only provide you with more control over the ads on your sites, but will also have a positive revenue impact and may even help with the profiling of users.