Gears of War 2 gets Update 4 release notes but no date
Epic's Rod Fergusson has said that Title Update 4 for Gears of War 2 has not passed certification yet so there is no release date to announce at this time.
However, he did provide a list of all the improvements, fixes, new achievements, and more.
The list also includes how much experience you will gain during Horde mode.
Full thing over on the official forums.