Unfortunately, Blackboards' patents preclude this from becoming a reality. For the next 15 years, Blackboard has an exclusive right to practice this "virtual classroom" business method.[1]
Their patent pledge[2] promises that they will not assert their rights against any open-source or home-grown initiative, which is why Stanford et al. are able to get away with hosting their own content in this format.
It's a harsh reality that by itself makes the case for patent reform.
See here: http://ideashower.posterous.com/idea-platform-that-universit...
If anyone wants to work on this, contact me :)