Halo 3 Recon comprised of two parts
Single and multiplayer sections distinct, says Bungie man
Bungie game developer Brian Jarrard has revealed to gaming blog Joystiq that Halo 3 Recon is best viewed as two separate products.
Apparently, the new singleplayer campaign is best viewed as a unique story and experience in its own right, while the multiplayer side of things is more of an enhancement over Halo 3's online mode.
"Think of Halo 3: Recon really as two games in one. You have the new Recon campaign that is a separate ‘title ID’ and includes 1,000 GamerScore and Achievements, etc. It’s campaign only," Jarrard explained.
"The multiplayer maps are more Halo 3 goodness, still considered ‘regular’ Halo 3 content and the multiplayer stuff is interchangeable in that regard. If you purchase the Mythic Map pack via the Xbox Live Marketplace early next year, but your friend doesn’t get those maps until the Recon disc comes out, they will work together just fine."
Halo 3 Recon is due out in the spring of next year.

Comments
Actually, the new maps are coming out in Spring, but the new maps are coming out in Fall 2009.
I NEED RECON!