According to this Evil Avatar post, Epic and Microsoft are planning to release five Gears of War maps as free DLC for the sequel. Provided you buy a new copy of Gears 2.
Previously, it was thought that Gridlock and Subway would be the only gears 1 maps making a return. Well, Epic is doing something different. There will be release day DLC that will contain those two maps, Canals, Mansion, and Tyro Station. These five maps will be free of charge but the only way to get them is if you receive a voucher, which every NEW copy of the game will have.
The info comes from the latest issue of GamePro, apparently.
More through the link.