A secret group within the UNSC that specializes in making assassins to destroy threats and try to harness the secrets of the Forerunners. John is one of the members. Project Hexagon is run by 6 leaders that keep their real position in the UNSC secret. The Project collects ships from both ONI and the UNSC. They convert entire fleets to join the cause by sharing all the information they have. Every 7th Day of the 7th Month, there is a meeting held for the largest fleet of Project Hexagon.
Do you think there will be a mention of the Forerunners in Halo Reach. My guess is that the game will end with the remaining Noble Squad rushing into Castle Base where there might be a mention of the Forerunners.