There's a large penguin on Steam's about page , so either TF2 has got itself a surprising 10th class, or Valve have released Steam's experiments in Linux delivery to the public.
It's the latter (although I really wouldn't put it past the TF2 team). Now anyone can join the Steam Linux beta, simply by clicking the install button from one of the relevant operating systems.
So far there are only 36 games available to try for the service, but between Team Fortress, Red Orchestra, Unity of Command and the selection of indie games, there should be plenty to keep you busy for now.
Valve have also set up a GitHub repository for bug reporting on any issues that will (inevitably) arise at this beta stage.
Anyone planning to take a look?