On the accelerating expansion of the Universe

Jed and I were discussing this awhile back: why does the Universe accelerate? Lots of theories out there, the foremost among which is "dark energy," but where does it come from? What the hell is it? New theory:

http://www.fqxi.org/community/articles/display/134

If this is true...consider my mind blown.

EDIT: In the same vein: http://bmgoau.nfshost.com/milkyway_spitzer_zoom/spitzer.html

Really, really cool.