Boo and Microsoft?
I am no PR guy but ...
I came across this post first on the weblogs.asp.net site and then saw it mentioned in Trumpi's blog post . I tried to comment in on Trumpi's post - both yesterday and today from 2 different machines - but no luck hence this post.
If you did read the post I would recommend going back to the original post from Scott and noting the comments from Scott Guthrie and others. The Boo page was last updated in 2005 and as this post (Jan 06) indicates it is fine to release extensions to Visual Studio under open source licenses.