It's always interesting when major changes happen and nobody seems to realise until a week later. On January 24th, Valve added a bunch of games to the Impulse digital download system, with a remarkable lack of fanfare.
Realistically, once you get over the initial shock of Valve stocking its games on a rival's digital shelves, it makes a lot of sense. That rival is owned by major gaming retailer GameStop, who (presumably) sells the odd Valve game or two in its bricks-and-mortar stores. It's a natural progression, then, to stock them in the online world as well.
Currently available on the system, offering "more quality gameplay than you can shake a crowbar at!":
The last laugh's with Valve, however: You might be able to buy these games on a rival's system, but each of the games must be activated on Steam before you can play it. So, y'know, you still have to install their system, too.
I like video games, fishing, Depeche Mode, long walks on the beach, writing discussion papers and cups of tea. Not necessarily in that order.
Jimmy the Geek