Not "hesitant slide"
It's not a bloody "hesitant slide towards open source"! It's an and out obvious attempt to "embrace, extend and extinguish" the very concept of "open". By releasing this code, they can later claim that REAL open source developers copied it, and then sue the living daylights out of them. It's the one piece that was missing from the SCO lawsuit: evidence. Now Microsoft have primed the pump for another go.
This article has what I consider to be the right take on the issue:
(which was referenced by Groklaw).