I've read about the sharing with friends and family thing...and it's absolutely awesome. Since we're a large community here, many of us have friends from hundreds of miles away. Lets say one of those friends buys a game you can not afford at the moment - When he/she finishes playing that game, you can simply go to their library and play it. And, with the +1 feature, you can have one special friend at a time play the same game as you. So, if you get a good co-op game, and want to play it with a certain person who can't afford it, you can +1 them and bam, there ya go, co-op.
Think about the money you could save with that. Sure, you'd have to wait until the person is done playing, if said friend doesn't +1 you, but I sure as hell wait 2-3 weeks for a free game.