1. Apple Steam Console
It was reported (albeit incorrectly) awhile back that Apple CEO Tim Cook had paid a visit to Valve. The things that Apple and Valve may have talked about were hotly speculated, at least until it was discovered that the report had been completely fabricated and regurgitated thoughtlessly by countless news sites and blogs without a single person bothering to check the legitimacy of the original report.
Valve may be working on wearable computing as an R&D project and it may have some interest in creating its own gaming system, but Apple and Steam are unlikely collaborators. As it is, Valve can barely get Steam to work without a hitch on the OSX. A hardware-based collaboration between the two is simply out of the question.
