In the same way it did with Comcast and Verizon, Netflix has struck a peering agreement with AT&T to bring subscribers' buffering woes to an end. This news was first rumored earlier today, and later on confirmed by AT&T in a statement saying, in part, "We’re now beginning to turn up the connections, a process that should be complete in the coming days."
The interconnect agreement was struck back in May, according to AT&T, with work having been done since to get the ball rolling. Given the above statement, it seems there is only a short while left before subscribers on the network will be seeing their Netflix quality jump.
These agreements serve to improve long-running issues users have experienced with videos buffering and presenting low stream quality. Netflix pays for direct network access, allowing it to avoid network congestion issues. Despite doing so, Netflix has been quite vocal in its disagreement with this -- something AT&T recently called "dramatic".
At the end of the day, it looks like AT&T customers will see their Netflix experience improve before those on Comcast and Verizon. This issue has played heavily into net neutrality debates, which you can read more about in the timeline below.