You may not have realized it if you were heads-down with your smartphone, but one of the most popular Angry Birds games is on Facebook: its social network adaptation,Angry Birds Friends, has racked up about 15 million active users. It's only appropriate, then, that Rovio complete the cycle with new plans to bring Angry Birds Friends to mobile. While details are slim, the company vows that the upcoming Android and iOS ports will maintain Facebook integration for rewards and tournaments, and they'll support both phones and tablets. We'll already have an inkling of what gameplay to expect courtesy of the web game, although we're not so fortunate with the release date -- Rovio will only say that the mobile Friends port is coming "soon."