Riot Games has begun preparing League of Legends for an eventual beta that will test the Team Builder functionality. Tucked away in the depths of the latest patch 4.3 notes, Riot Games mentions that "some Team Builder assets are included in this patch in preparation for an eventual two-day live beta test."
Team Builder was first revealed back in October of last year. It's a feature designed to create a more cooperative Champion Select session as it allows you to pick your preferred role and attempts to match you with a group in which you can play that role. In addition to your preferred role selection, it will also try to match you with like-minded players in terms of overall strategy, such as double jungle, dual top, and things of that nature.
Unfortunately, Riot did not mention a specific date for the beta test but Team Builder has been available for test on the Public Beta Environment for quite a while now. Earlier this month, the function underwent significant testing on the PBE with players able to offer feedback on the latest changes.
