Oh Hallelujah: Steam Now Lets You Preload To Any Folder 

This may sound inconsequential, but I assure you: it is most certainly not anything of the sort. Previously if you wanted to preload a Steam game, you were stuck with good ol' C:-fault, which was both a) an inconvenient pain and also b) dumb. We've been able to download Steam games to any hard drive for quite some time, so the restriction on preloading made zero sense. Now Valve's fixed that - well, if you're using Steam's beta version, anyway.

Valve announced the change in an update, alongside a new Big Picture library section dedicated to screenshot management. Here are the patch notes:

General

• Fixed in-game overlay sometimes not activating on first hot-key press after game launch
• Games can be preloaded to any available Steam Library folder

Big Picture

• Added new library section for browsing and managing user screenshots

In-Home Streaming

• Worked around a crash in the latest NVIDIA driver (337.88)
• Implemented brightness controls for games like Dark Souls II and Thief
• You can toggle windowed mode on the client with Alt-Enter and resize the streaming window
• Desktop shortcuts will stream games if they are currently available for streaming
• Added 2’ streaming EULA dialog so you don’t have to go to the remote computer to accept it after installing a game.
• Fixed the menu bar showing on the client on Mac OS X 10.6

So nothing earth-shattering, but oh jeez thank goodness finally, etc etc etc.

Steam continues to improve little-by-little, though it still has a long way to go before it's ready for its own increasingly open, over-stuffed Future. One step at a time, I suppose, though. What blindingly obvious improvement would you like to see Steam get next?