EA and Valve have announced a retail distribution agreement between the two companies that will bring Portal 2 to retail shelves. The partnership was expected, as EA and Valve have already worked together to bring The Orange Box and both titles in the Left 4 Dead franchise to stores.
Valve will distribute Portal 2 for PC and Mac via its digital platform Steam, while EA will presumably distribute the game to retail channels for all planned platforms: PC, Mac, Xbox 360, and PlayStation 3.
In early November, Valve told Shacknews that Portal 2 would launch on April 20 for all platforms in North America. According to the press release today, Europe will be able to make portals on April 21.