http://store.steampowered.com/news/2503/

This weekend only, Call of Duty: World at War is on sale for 50% off the regular price. Play in single-player, Multi-player, or co-op modes as you are immersed in the most gritty and chaotic WWII combat ever experienced. Also includes the recently-released Map Pack 1: Four new maps, featuring the fan favorite 4-player co-op Zombies Bonus Mode in "Verruckt," a terrifying Zombie asylum located in the outskirts of Berlin.

Plus, earn double experience points in multi-player games this weekend during the sale.

I'm still just going to wait for modern warfare 2.

Same
IMO CoD 2 > CoD 5 except the fact cod 5 has nazi zombies >.

I bought CoD5 last night on steam for £14.99... great bargin for this game.  I just wonder how many copies steam has sold of CoD5 this weekend......

Sadly valve won't release figures but they will say increased percentage is all if they do

Yeah but why won't valve release sale numbers......  makes no sense, unless sale numbers are low.  Which I can't believe for valve games like CS, TF2, L4D.  Even for non-valve games, fallout 3 has been for the top 10 for a long time and also has CoD4.

The other day their were over 10,000 current players playing 'Killing floor' at once.  Check out the numbers for Plants vs zombies and is still at number 5 in the top 10 sellers.....