Straight from the horse’s mouth:

So you’ve been wondering what the Halo 3 Recon announcement was all about, huh? We’ve got all the info you can handle! The December issue of Game Informer Magazine has 10 pages packed full of info and screenshots straight from Bungie. We also have another 10 pages of our annual Holiday Buyer’s Guide featuring the coolest gear for all types of gamers. All of this plus much more so don’t miss this issue! Subscribers will also get some added content on Nov 17 when Unlimited hits right here on GI Online.

Just in case you didn’t figure it out by now, famed Halo developer* Bungie has reiterated that Halo 3: Recon will be the company’s last Halo game. Don’t worry, though: there’s a map pack scheduled for early next year and another one due for around the time of Halo Wars‘ release.

*Perhaps the company didn’t want to be forever pigeon-holed as “the Halo devs”?

The new expansion will pit you as an ODST marine aka New Hero and will serve as a prequel to Halo 3. We’ll have the teaser trailer up soon and box art.

Update: Trailer after the jump.
Update 2: Luke posted this snippit over at NeoGaf.

The word “stealth” here isn’t really a great word. This isn’t a stealth action game like a Splinter Cell game. This is a Bungie-made Halo game where you will play as an ODST, which of course, is different (and no, I’m not talking about how it’s different ;b) than playing as a Spartan super soldier. This isn’t Halo Cell, Ghost Recon: Halo, Republic Commandalo or whatever.

Edit: Forgot Call of Halo and Gears of Halo.

Details from the Xbox page.

To the delight of devoted fans across the world, at the Tokyo Game Show Microsoft debuted Halo 3: Recon, developed exclusively for Xbox 360® by acclaimed developer Bungie. This new chapter in the Halo saga lets you experience events leading up to the epic story told in Halo 3 through the eyes of a new hero in the Halo universe.

The stand-alone expansion, set to release in fall 2009, extends the award-winning Halo® 3 experience with hours of new campaign excursions and multiplayer gameplay. In addition, attendees were given an all-new glimpse of the Xbox 360 exclusive strategy game Halo Wars from Ensemble Studios. The campaign mode provided a thrilling taste of the revolutionary gameplay and new perspective of the Halo universe. Enjoy the full experience when Halo Wars hits retailers in early 2009.
Game Details

This new chapter in the Halo universe includes the following:

* All-new campaign content: The Halo 3: Recon campaign is an intriguing side story that takes place during the terrifying events leading up to the Master Chief’s return to New Mombasa in Halo 3. Experience the fate of Earth from the brand-new perspective of a special forces ODST (Orbital Drop Shock Trooper), adding a unique outlook and new gameplay elements to the events that unfold in the trilogy’s finale. While the feel of this new chapter greatly resembles that of previous Halo experiences, Halo 3: Recon will require you to employ more elements of stealth and cunning than ever before.
* Prepare to drop: Known for their courage, valor and, at times, insanity, ODSTs are among the fiercest UNSC soldiers, priding themselves on being the first unit deployed into hostile situations. While not as large or supernaturally gifted as their Spartan comrades, these “Hell Jumpers” more than compensate with their ferocious attitudes and unwavering nerve.
* Expanded multiplayer collection:No Halo experience would be complete without groundbreaking multiplayer content, and Halo 3: Recon gives fans more of what they love. With exclusive new maps and expanded Forge options, Xbox LIVE® Gold members will find more multiplayer content than ever before with Halo 3: Recon.
* Ever-growing community options: Enjoy all the great Halo 3 technological innovations, including Saved Films, screenshots, Campaign Scoring, and four-player co-op. All of the new multiplayer maps fully support the Forge editor, offering endless gameplay customization possibilities.