Daniel Lemire's Blog | The learning pillAnswer: probably the corporation that built StackOverflow.
Given a choice between a college graduate in Computer Science and someone who has a leading reputation on stackoverflow, which corporation would pass on the college graduate?
Draw your own conclusions.
PS I don't mean StackExchange will hire people with a good reputation on their own system. I mean StackOverflow was built by a team of people who valued ability over credentials. You'll notice Jeff Atwood, one of StackExchange's two co-founders, does not list "look at their college transcript" on this list of "how to hire a programmer." Joel Spolsky, the other co-founder, puts more emphasis on college than Atwood, but he's said that's for the pre-selection effect. He's as happy to see McKinsey or the Marines on a resume as Harvard because what he's interested in is outsourcing the effort of screening candidates to other selective organizations. They probably discussed their hiring process half a dozen times on their podcast, which was extremely educational about how good software companies actually operate.
PPS Spolsky has repeatedly written that he's a big, big fan of hiring directly from his internship program. He recruits sophomores more than seniors, IIRC. So while he places import on college, he doesn't seem to place much on having finished college.