Microsoft are gearing up for their second part of their recent Xbox One update, the second part of which is the bigger side of things and includes some much needed multiplayer focused updates and changes to the Xbox OS including a new party system and friends/recent players activity. The update which is due out sometime in the first two weeks of March. It will also include and update for Titanfall to patch the analog twitchy behavior that effects the game.
Microsoft will be sending out Xbox Live messages to some users regarding early access to the latest firmware in an effort to test it out before the official launch, but they will also get all future updates before official release for the same reasons. Selected users will simply receive a token that will allow them to register for the preview program.
Source: Xbox Wire