Epic Games is planning a double XP weekend for Gears of War 2 to celebrate America's independence from the tyrannical British (guilty).
What's more, Title Update 4 should hit beforehand, according to executive producer Rod Fergusson, meaning that Horde mode will also confer XP.
That's particularly relevant because the other part of Epic's weekend celebration is a change-up to Horde that means Ticker squads (a bunch of Tickers spawning simultaneously) show up more often and every 10th wave will be comprised of nothing but Tickers.
If you haven't played for a while and can't recall, Tickers are those little dog-sized bastards with time-bombs on their backs who run up to you and explode. Remember to melee them for extra gamerpoints (although, er, probably not in ranked Horde, unless you want to wind up your comrades).
According to Fergusson's Gears 2 forum post, it all wraps up on Monday, 6th July, at which point the game returns to normal.
With that said, the benefits of Title Update 4 are of course permanent. Check out the release notes to see what else it introduces.
Oh, and don't forget that the Dark Corners expansion, introducing a new campaign section and several multiplayer maps, launches on 28th July - and that it's going to be cheaper than originally advertised.