Seems like all they'd have to do is add value to advertisers using the existing ad-word engine. The plan is always the same for any internet holding - build up user base, then invest heavily in the advertising engine to add value for the true customer, advertisers. If you listen to FB conference calls, it's always "we want to build the service to over a billion users, then we'll work hard to create the ad engine to get advertisers as much value as we can."