Linux Libraries Appear In Left 4 Dead Demo

Earlier this year we shared that Valve's Source Engine is coming to Linux after receiving some information that pointed in this direction. In addition, a year ago Valve Software was publicly looking for a senior software engineer to port Windows-based games to Linux platform. There have long been rumors and hopes among Linux users that Steam games would become naively available for Linux, but we have additional confirmation that Valve Software has ported their Steam game client to Linux. In Valve's most recent title, Left 4 Dead, there are shared Linux libraries shipping alongside this Windows game client.
Source:
Phoronix.com