[UPDATE] 343 Industries has confirmed that the Halo 3: ODST listing is not final.
Halo 3: ODST will see its addition to Halo: The Master Chief Collection this Friday, 29th May according to a pre-preemptive release of the supporting page at Xbox.com. The page exists when searching for Halo 3: ODST but clicking the link now goes to a dead page. However, Xbox Dynasty managed to catch the screen before it went offline which confirms the release date along with the 8.1GB download size for the game.
Halo 3: ODST is being offered for free to those who purchased Halo: The Master Chief Collection before the 19th December 2014 as a form of apology for the rocky launch the collection of Halo titles got on Xbox One. The page caught before it went offline does not mention the price for those not eligible for a free offer.
Halo 3: ODST will run at 1080p at 60 frames per second matching the other titles in the series.
Halo: The Master Chief Collection is available for Xbox One.