Facebook has already displayed self-service advertising on events and public profile pages, now those ads are getting more interactive. You'll be able to become a fan of an advertised public profile page by clicking on the "Become a fan" button without leaving whatever Event or Page. Same with RSVPing for advertised events. If you take one of these actions, like most other activity on Facebook, an item about it will appear for your friends to see.
Facebook doesn't want people to have to click through to new pages if they don't want to -- even though more pageviews generate more banner ad impressions. Instead, the social network is trying to figure out how to make ads more meaningful to people within an easy-to-use interface. More on the announcement, here.
Today's news isn't a big new innovation, but rather an illustration of how the company is trying to fine-tune the advertising experience -- something that seems to be working, judging by the company's self-reported revenue growth.