IGN.com has provided a handy little recreation of Microsoft's official information sheet for Halo 3 Recon, and it includes confirmation of four-player co-op within the standalone campaign.
Also confirmed is the trademark plethora of Bungie features, including Campaign Scoring, detailed stats, replay saves, screenshots, and Forge options for the new multiplayer maps. (Who just mentioned multiplayer on Co-optimus? Not me...)
UPDATE: Most of the same information is available here at Xbox.com, but we'll give IGN credit, since that's where I found it.
You can view the entire fact sheet after the "Read More" link.
Title: "Halo 3: Recon"
Publisher: Microsoft Game Studios
Developer: Bungie
Format: DVD for the Xbox 360 video game system; Xbox LIVE-enabled
ESRB Rating: Rating pending
Availability: Fall 2009
Product
Overview: Developed exclusively for Xbox 360 by acclaimed developer Bungie, "Halo 3: Recon" is a stand-alone expansion that extends the award-winning "Halo 3" experience with hours of new campaign and multiplayer gameplay.* The release adds a new dimension to an all-encompassing universe that gamers around the world have known and loved for more than six years.
The new campaign chapter predates the events that unfold in "Halo 3" and gives players a new perspective through the eyes of a new hero in the "Halo" universe. New multiplayer maps ensure that the award-winning Xbox LIVE experience of "Halo 3" continues to thrive.
Top features include 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 will greatly resemble that of previous "Halo" experiences, "Halo 3: Recon" will require players to employ more elements of stealth and cunning than ever before.
- A new hero: 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 full Forge options, players will find more multiplayer content than ever before with "Halo 3: Recon."
- Ever-growing community options. Players will continue to 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 for fans.
Source: Xbox360.ign.com