Sometimes it's under a bogus unapproved license written by Microsoft lawyers. Sometimes it's under a Microsoft license its lawyers got through the OSI, after much wailing-and-gnashing-of-teeth.
But this is the real deal. This is Apache 2.0 licensing.
And this is pretty cool code, too.
As Ray Valdes of Gartner Group has noted, this can also protect against cross-site scripting, an increasingly common attack of hackers against Web sites of all types. So it is a cool thing.
If this move is followed up by others along the Apache line it will be a very good thing. It would not help my traffic if Microsoft becomes a non-controversial word in the open source community, but it will help open source.