Valve have announced that they've picked up the distribution rights to some Eidos games, and will be selling them over Steam. Gabe Newell:

Offering legendary action franchises in complete sets and working with Eidos to deliver new releases is a great step forward in our efforts to expand Steam's offerings, and to do so in ways that provide highest value to customers.

Releasing "complete sets" (as in, potentially every Hitman game at once) is a good idea. Selling brand new, upcoming Eidos games over Steam? Even better. The future? It's now. Luke Plunkett

Eidos Launching With Steam [Steam]