The company won't have any official presence at this year's show.
Valve made the announcement with a rather bluntly worded e-mail.
"Lots of folks have mailed asking about appointment times, etc. with Valve," said the e-mail. "Well, we are not showing any titles at this year's show. So no appointment is needed."
So if you were expecting Half-Life 2: Episode 3 to make a surprise showing, well...sorry. You'll have to wait for 2012.