It is a game in development by Peter Jackson's recently formed games studio Wingnut Interactive that has been described as "more of an interactive movie [in comparison to other video games]," "[sort of a] Gears of War meets Halo in terms of gameplay," and "something that's really good and hasn't really been seen before."
There are also rumors of it being episodic in nature and being released as a series of Xbox Live Arcade games.
There has been very little news since it was first announced, the most significant revelation being its working title (which is why you know it as Halo Chronicles as oppossed to "Unamed Peter Jackson Halo Project").
"This facility has a successful utilization record of 1.2 trillion simulated and one actual.
It is ready to fire, on demand."
-2401 Penitent Tangent