There's a possibility that gamers on Steam will soon be able to "borrow" games from each other. Users testing a beta version of the service have posted code on Neogaf that could point to a possible change in tact from Valve, potentially allowing gamers to lend each titles from their respective libraries.
"SteamUI_JoinDialog_SharedLicense_Title" "Shared game library"
"SteamUI_JoinDialog_SharedLicenseLocked_OwnerText" "Just so you know, your games are currently in use by %borrower%. Playing now will send %borrower% a notice that it's time to quit."
"SteamUI_JoinDialog_SharedLicenseLocked_BorrowerText" "This shared game is currently unavailable. Please try again later or buy this game for your own library."
As it stands, when a game is purchased on Steam it is locked to a user's account and can't be moved. Are Valve planning on making changes that will allow us to share purchased content? And will publishers be enamored of the idea? We'll have to wait and see on this one, but if this report proves accurate there'll be a lot of happy Steam users out there.