Valve Software sends word that their cooperative focused Zombie apocalypse shooter Left 4 Dead is now available for the Mac. Mac supported is accompanied by several other general bug-fixes
and drops in the middle of Valve's Halloween festivities.
In addition to a big Steam Halloween Sale
Valve have also added a bunch of quirky features to Team Fortress 2 that includes new achievements, new Mann Co store items, a new Map with exploding pumpkins and a "Headless Horseman" NPC that generates randomly during matches. More specifics on that one can be found over at teamfortress.com