Go get it if you don't have it http://store.steampowered.com/app/550/?snr=1_7_15__13&fb_source=message
Offer ended at 10AM PST. Don't know the swedish time zone off the top of my head but 10AM PST was 4 or 5 hours ago.
I bought it a while back too. But, now that it is free, I can get it on my bros steam account and we can play together. (Already got it)
I got left 4 dead 2 (along with a shit ton of other games) around 1-2 months ago when I bought the Valve Complete Pack 50% off in the autumn sale. 24 games for 36€, freakin' amazing.