The number of Linux titles has grown to 39 as of this writing, and rumors suggest that more are on the way. No one is saying what those additional titles might be, but rumors of other developers watching this closely are not just a myth.
Because of the move to an open beta of Steam for Linux, we have to believe that a full release is getting much closer. Those who have an interest should follow the Steam for Linux community site to get the latest information.
Check out the Steam for Linux site here.