Valve’s digital entertainment platform has surpassed the 15 million account milestone.

Valve confirmed that it has seen a sales growth of 158 per cent over the 2007 holiday period, citing the launch of Call of Duty 4, Bioshock and The Orange Box as the reason for the growth.

"PC gaming is thriving, and has evolved into an era of constant connectivity," said president of Valve Gabe Newell. "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."