"We went around to Yahoo, Microsoft...and anybody who seemed like a likely candidate to build something like Steam," Valve marketing veep Doug Lombardi told GamesIndustry.biz in an interview. "We went around to everybody and asked 'Are you guys doing anything like this?' And everyone was like 'That's a million miles in the future ... We can't help you." Valve, of course, proceeded to single-handedly bring the future to the present (which is now nearly five years in the past) and the rest is history.
Readers without a vested interest in Microsoft and/or Yahoo should check out the full interview, where Lombardi talks about piracy, independence, and the future of PC gaming. Anyone involved with those two companies would probably be better off visiting this handy site first.