What gives credence to this? A novel called 'Halo: The Fall of Reach' was published in 2001, a prequel to the original game. Four Halo projects are said to be in the making.
Aspoints out, three of the four things as of September were Halo Wars, something called Halo: Chronicles which is believed to be linked with Peter Jackson, and Halo 3: ODST. Is Halo: Reach the mysterious fourth project?
The anonymous tipster who gave Kotaku the grab says the game "is slated for Fall 2010, and this forum plus an ODST forum will go live June 1." Take your salt now videogamers.