Defacto standards, I believe, are a good way to inform the development of real standards. Standards developed the other way around, at least in the tech industry, have had a habit of taking a very long time to reach end consumers… for example, how many decades has it taken for your average web user to gain access to a fully CSS2-compliant web browser? How many more decades will it take for OASIS’s OpenDocument format to supplant Microsoft Word and its *.doc files?
Also, as others have noted, this is the first time Microsoft itself is distributing an open-source project with one of their products. A sign of things to come?