Valve believes the upcoming launch of Steam for Mac is "the biggest event in Steam's history since the service was first launched".
Speaking to Joystiq, John Cook, director of Steam development at Valve, said, "There are several people involved, from the UI team working on Mac support in the Steam client to graphics engineers working on the native version of Source and our games. It's a big effort."
He said that persuading PC developers to port their games to Mac is "one of the primary goals". adding, "Steam has proven to publishers and developers that the PC games market is still thriving, it just needs to be attacked from more directions than retail. And like Steam on the PC, it took some proving with Valve titles to get third parties interest. We believe Steam for the Mac will be a similar, but much shorter, process."
Cook said that the company is talking to over 1,000 developers and publishers about bringing games to Mac via the online distribution system.