Another bonus XP event is slated for http://www.trueachievements.com/Gears-of-War-2-xbox-360.htm
and this time GearsViking
has also stated that there will be a horde bonus for those seeking the Seriously 2.0 in Gears of War 2
It’s a 10X Thanksgiving for Gears of War 2 players! From 12 AM GMT November 19 (7 PM ET November 18) through 9 AM GMT/4 AM ET November 29, Gears of War 2 players will earn a 10X experience bonus in all online multiplayer modes. Once you’re stuffed with turkey and potatoes, go online and rack up the experience.
If you need to purchase the game to take part in this bonus XP event (or repurchase it like myself), do not forget to pick up the Game of the Year
edition which includes a download code for all of the multiplayer DLC maps as well as the DLC bonus chapter.UPDATE
has stated the horde tweaks may be a little bit "grindy"...