Here's an interesting, if random, aspect to the brewing war between Valve's Steam service and EA's new rival, Origin: you can use keys from the former on the latter.
Running some tests on the competing platform, PC Gamer found that some Steam keys (the codes you can use to activate a downloadable copy of a game), for games like Battlefield Bad Company 2, Dragon Age Origins, Mass Effect 2, Dead Space 2, Alice: Madness Returns and Dragon Age 2, worked when you used them on Origin.
That's a neat touch. What it means is that not only can you launch your Steam games from within Origin, but once launched you'll be able to use Steam functions like in-game overlays.
EA Steam keys can be activated on Origin [PC Gamer]