Microsoft and Epic have confirmed the first expansion of Gears of War 3 - called Horde Command Pack. You're getting quite a bit of content for your 800 points (free with the Gears of War 3: Season Pass). The DLC contains three new maps (described under the screens below), three new playable characters, two new weapon skins, and 250 new achievement points to gain - as well as new Horde fortifications.
The new fortifications for Horde mode are as follows:
• Command Center - A brand new type of fortification that allows you to call in fire support from sniper teams, mortar strikes and even multiple Hammers of Dawn.
• Decoy Upgrade - A new fortification level that turns your decoy into an Onyx Guard bot that will fight in your defense.
• Sentry Upgrade - This upgrade adds a fire bolt sentry that deals much more damage and is very effective against Berserkers.
• Silverback Upgrade - This advancement allows you to upgrade your Silverback exo-suit with devastating rockets and extra levels of repair cost reduction.