Having added 5,000 more Linux gamers to its limited public beta test program last month, Valve Software has recently announced that a "large mount" of additional volunteers will be let in.
Another sign that we getting closer to the official launch is that Linux system requirements were added to several games on Steam. The list of games with Linux support on the CDR web site has increased to 68 titles.
If you are interested in the Beta tester program and haven't signed up yet, you can do so on the Valve Software Linux Survey page.
It is also possible to get the beta version for Ubuntu without the official invitation.