In couple of years, Valve and its online service Steam became a key actor on the online game market (online purchase and online games). Some rumors indicate that the company would like to go one step further by releasing a Steam Box, an online-dedicated game station. Components already exists in our Mac or PC: Intel CPU Core i7, 8 GB RAM and a AMD GPU. With such hardware one could run all PC games.
It seems that Valve does not plan to compete with Sony PS3, Microsoft Xbox or Nintendo Wii, but rather try to find its place and secure its market against forthcoming services and products to be released by Apple in a near future (something like a Super Apple TV?). Overall, Valve might have decided to enter the online game market for selling games and services and to prevent the Apple AppStore and its corresponding service from Microsoft to capture the entire market. Indeed, Mountain Lion and its Game Center will allow you to purchase games online and play them on any Apple hardware/devices (if different versions exist). It could well be the only solution for Valve to secure its business for years ahead.