Origin is following the leads of PlayStation Plus and Games with Gold by offering selected free games across limited times - the difference is you don't pay to be an Origin member. It's unclear how often Origin's new On the House program is going to trot out its freebies, but for starters members can get dismembering with third-person survival horror Dead Space, which is free to download now.
According to EA's FAQ, "once you've claimed your game, it's yours to keep." You've also got plenty of time to claim Dead Space, because it's staying free to download until May 8.
I guess Origin has begun taking notes, while it's a so so service giving out free games is always nice.