Valve's new Steam will go beyond just games and offer all sorts of software while still providing the same Steamworks benefits like easy/automated installation, automatic updating, and being able to safe your work into the Steam Cloud.
The launch will happen on 5 September.
This move will now align the Steam client into much greater competition with Microsoft's forthcoming Windows 8 store as well as Apple's App Store and Canonical's Ubuntu Software Center, etc.
The announcement can be found at SteamPowered.com.
Coincidentally, I was questioned about Steam supporting applications just a few days ago along with a rumoured Steam Linux distribution and Steam Box on the Linux Action Show podcast -- the video is available from that article. I also mentioned another announcement was expected very soon, and as we see now, a new Valve Software announcement did happen just three days later. (Anyone with additional questions or seeking other thoughts can potentially get them answered via letting me know on Twitter at @MichaelLarabel -- or just following there for when additional information is shared.)
SIGGRAPH LA 2012 is also happening right now and Valve will be showing off their Linux work where more excitement will be had.