Speaking to VideoGamer.com at E3 last week, writer Chet Faliszek talked up Valve's relationship with Microsoft when asked if a PS3 version had ever crossed anyone's mind.
He said: "If it crossed someone's mind it wasn't the focus. The focus was 360 and PC. A) it's what we develop on. B) it's the platform we think lends itself to the interaction of our game the best."
Faliszek also revealed some interesting titbits on the relationship Microsoft shares with Valve, describing Microsoft marketing staff as "hardcore" Left 4 Dead players.