Valve announces that the Steam Families feature is out of beta, and has officially launched for all users. This allows you to invite up to five family members into a group to share your game library. Each gets their own saves and achievements, and you can set up age restrictions so the kids don't get in over their heads. Here's the intro video and there's a FAQ to fill in all the details. Here's more:

When you join a Steam Family, you automatically gain access to the shareable games that your family members own and they will also be able to access the shareable titles in your library. The next time you log in to Steam, this new 'family library' will appear in the left column as a subsection of your games list. You maintain ownership of your current titles and when you purchase a new game it will still show up in your collection.

Best of all, when you are playing a game from your family library, you will create your own saved games, earn your own Steam achievements, have access to workshop files and more.

Family Sharing enables you to play games from other family members' libraries, even if they are online playing another game. If your family library has multiple copies of a game, multiple members of the family can play that game at the same time. For a more detailed look at how Family Sharing works, see the FAQ below.