This week the folks at Valve have introduced a new Beta release - the second of two so far, that is - of SteamOS. This operating system is delivered in an ISO file, coming now with the ability to install to non-UEFI systems. This update includes work done by the developers known as directhex and ecliptik who created the system called "Ye Olde SteamOSe".
This second release of SteamOS in beta form is still part of a system that Valve warns the public is possibly volatile. You're certainly not going to want to install this piece of work on a system you're especially attached to, as it could - if you install it wrong - wreck the innards of your computer. There's a distinct possibility you wont be able to get back to square one, that is.
Valve notes that this release also includes dual-boot options as well as custom partitioning, especially important if you want to run Windows alongside this Linux-based system in the near future. Linux remains the base here, and the whole dual-boot system is included in the "Expert Install" option on the download.
"PLEASE note there has been very little testing on this, especially any kind of dual-boot setup. So don't install it on any machine you are not prepared to lose." - Valve release
This release includes the warning published above, straight from Valve. This is not an install you're going to want to work with if you're simply interested in SteamOS on a hobby level - it's not that kind of drop.
Meanwhile you've got the option of diving into SlashGear's SteamOS tag portal for more information on the system than you could possibly want. We've got several interviews published with several more on the way, up close looks at systems coming your way, and details on the release from top to bottom. The SteamOS Github is also open now for heavy discussion straight through release - later this year, in the 3rd quarter at earliest, mind you.