Well well well, this is interesting…
This essentially allows you to share your complete games library with upto 10 other steam users.
It should be noted that this is apparently an all-in or all-out solution, so you can share everything or nothing, essentially.
The way it seems to work is that there is a ‘sharer’ and a ‘borrower’ account.
The borrower requests access, is approved by the sharer, then the library is shared. It looks as though this request can even be performed within ‘Big Picture’ mode. Win!
After this point the borrower can play any game at any time from a sharers library. If the sharer decides to play one of their games (Again, an all-in or all-out approach) then the sharer is given a few minutes to exit the running shared game before it is closed.
They are also apparently given the option to buy the game, which is interesting.
I can think immediately of how I want to use this; On my Media Center, where I’ll have my borrower account share games from my own personal account. This gets around an annoying issue where I have to re-login if I start ‘Big Picture‘ mode while the Steam client is running on my desktop…
I can also share games with my family and friends who I would like to try a game.
Something to be aware of is that your savegames are not shared across accounts…