Bright Side of News analyzed the results of the Steam Hardware Survey July 2009 to discover the latest trends among gamers. You can check out the results over here. Here's a snip about GPUs:
Looking at graphic cards, nVidia has 65.38% of all Steam users, while ATI covers 27.26%. During July, 1.72% of all users upgraded to DirectX 10 compliant hardware, mostly ditching their old DirectX 9.0c graphics cards such as GeForce 6/7 and Radeon X800/1K series. Biggest winner in GPU wars is ATI Radeon 4800 series, taking around 160,000 new users [0.77% MoM growth, 7.23% overall].
When it comes to available memory, 35.75% of all users have 2GB of system memory [1.19% decline], followed by 3GB [1.17% MoM growth, 27.33% overall] and 1GB [1.26% loss, 16.35% overall]. Extrapolating these numbers, we can see that majority of new upgrades either feature 4 or 6GB of memory, limited by operating system [3.25GB is usually the maximum 32-bit OS can see]. Moving on to GPUs, vast majority of video cards feature 512MB [0.46% MoM growth, 38.69% overall], but 896MB [0.56% growth, 3.19% overall] and 1024MB [1.19% growth, 9.63%] are making steady progress. We estimate that next month, share of graphics cards with more than 1GB of video memory will surpass 10-12%, given the Back-To-School shopping bonanza.