A number of sources are confirming that Valve isn’t planning to show anything new at E3 this year. However, the fact that they are not showing anything on the floor doesn’t mean that they might now show something in one of the press conferences.
Whispers suggest that Valve could have one of its titles featured in the Sony press conference. This rumor makes sense, due to the fact that they showed up at Sony’s press conference last year.
We think nothing is set in stone, and we actually expect Valve to show up in one of the press conferences; but it is really more of a question of which one.