From Michael Feldstein, via the OLDaily.
It looks like Blackboard paid for Google adwords to have ads for Blackboard appear when people searched for "Open Source LMS" --

Unfortunately, the Blackboard ads appeared under the heading "Open Source LMS" creating the appearance that Blackboard is an open source product.

It appears that Blackboard has pulled the ad. And here I was, expecting to see a link to the "Blackboard Free Download" page, and their Community Support wiki.