The job listings at Junction Point Studios site all specify that this will be a Source engine project. Spector himself is quoted as saying "We are currently working with Valve on a new game using the Source Engine to be delivered via Steam, and are looking for top talent from within the industry to help us out."
Spector has long been an outspoken opponent of current game market paradigms with regard to funding and distribution and the chilling effect they have on creativity and innovation. His rant at last year's GDC referred to Steam as "a good start" at addressing these problems. Clearly he's trying to get behind it and give it some content that will push it to the next level.
Recent statements from Spector at the Montreal International Game Summit also potentially could be addressed by Steam. "Sadly, sticking with the tried and true is going to result in financial success for some, for a time. But stagnation is not the friend of any medium. And anybody who thinks it is (is) going to go out of business."