You would think that, as time goes on, more and more Steam users would be adopting better hardware for their PCs. The Steam hardware survey for June 2012 tells us that may not necessarily be the case, as the company actually saw an increase in lower-end PC use over past hardware surveys. Take, for instance, the number of computers that use Intel Integrated Graphics - while NVIDIA and ATI GPUs are still by far the most common, in June Steam saw the use of Intel Integrated Graphics rise to 11%.
There was also a rise in the use of single and dual-core systems. Systems that use DirectX 11 and DirectX 10 GPUs rose ever so slighly (both by less than one percent), but the number of systems using DirectX 9 rose by 1.5%, meaning that DirectX 9 systems are now used by almost 20% of Steam's user base. Also of note are the most common resolutions: 25% of participants in the poll are using 1920×1080, 18% are using 1366x768, 10% are using 1680x1050, and finally, 1600x900 comes in with 7%.
PCGamesN points out that this rise in older hardware could mean that more users are installing Steam on their laptops. There's also the fact that indie games are all the rage at the moment, and those don't usually require high-end hardware to run. Indeed, you can enjoy a lot of Steam's game without having a beast of a rig, and considering that indie games are generally much cheaper than major releases by big publishers, it seems like that may be one of the reasons why we're seeing more middling PCs accessing Steam.
It's also worth pointing out that a bug in the system recently discovered by Steam prevented new computers from being included in the monthly surveys. While the bug was present, only computers that had participated in the poll before were polled again in recent hardware surveys, meaning if you recently installed Steam on a new PC, it may not have been included in the results. The bug has since been fixed, but it's causing all of this data to appear all at once instead of over time as it would have normally. Still, despite the bug, this is an interesting development, and it will be exciting to see where the data goes in future hardware surveys.