So far, most of the information has been pretty light, with the people (people?) manning the account using it to engage people about what they'd like to see on Waypoint and giving away some DLC codes for the recent Halo Wars add-on.
Today, however, @HaloWaypoint settled the score on a long-running Halo rumor with this update:
This one had been kicking around for ages, originally claiming that the developer of Borderlands was working on Halo 4. This recent denial was probably sparked by a recent Eurogamer interview with Gearbox's Randy Pitchford, where a question about Gearbox's involvement with Microsoft's franchise was quickly shut down with a "we can't talk about that." That's not a very poker-faced way to address something that's completely unsubstantiated.
For the record, Gearbox is NOT working on a Halo title for Microsoft.
If I were a betting man, I'd probably put money behind a theory that Gearbox was, at one time, working on something Halo-related, but plans changed and the developer moved on. If you're interested in see what Gearbox is actually actively working on, check out our recent interview with Randy Pitchford to hear more about Borderlands.