Valve wasn't just tooting their horn earlier today when they said two million copies of Left 4 Dead 2 had been sold so far. Well, okay, they were tooting their horn - but they had some useful information to impart, too.

“Left 4 Dead 2 is off to a great start with strong support at retail and great reviews from the press,” said Valve marketing boss Doug Lombardi. "Meanwhile the title has already been played by over 1 million Xbox LIVE Gold account holders, and news regarding L4D2 DLC 1 is coming very soon,"

After its release, Left 4 Dead received a new game mode and mini-campaign as downloadable content. It took them about five months to release the first bit, though. It sounds like they're planning to be more prompt with the sequel's DLC.