Steam now has over 15 million accounts, according to Valve.
It's also experienced year-on-year sales growth of 158 percent, the developer/publisher said yesterday, although it didn't specify which exact period that covered.
Steam has grown considerably in the last year. Having built its popularity on Half-Life 2, the game's second episodic instalment - part of The Orange Box - helped to drive sales while other publishers continued to back it with high-profile releases like Call of Duty 4 and BioShock.
Already this year GSC has said it will partner exclusively with Steam for the digital distribution of S.T.A.L.K.E.R. Clear Sky (Koch Media is handling retail distribution in most of the world), and Valve's own co-operative multiplayer zombie game, Left 4 Dead, will also look to take advantage.
The company also promises more community features to add to those launched in 2007, and points to the recent launch of Steamworks - a service that gives developers and publishers control over areas like product key authentication and copy protection - as an example of the good work still going on.
Handily for Steam - or perhaps thanks to it - "PC gaming is thriving" in the words of Valve president Gabe Newell. It's "evolved into an era of constant connectivity," he says.
"That connectivity gives us the ability to have a much better relationship with customers, not just for delivering our games, but across all aspects of our business - including the design, development, and support of our games.
"Features like Guest Passes, Free Weekends, Gifting, and the Steam Community have been very well received both by customers and the developers who are using Steam.
"We are accelerating our release of new functionality in the next year as well as finding new ways to work with our partners such as the release of Steamworks, which allows them to bring the many benefits of Steam to their packaged products."