Windows Live Writer - Half Open?
Microsoft's Windows Live Writer, which allows you to post to blogs directly from a WYSIWYG desktop app, is hardly open in the traditional sense, although it is free. However, it's half-open in the sense that it supports non-Microsoft blogs like Blogger, LiveJournal, TypePad and WordPress.
I've not been able to try it, because it requires the .Net framework which I prefer not to have on my Windows boxes since it's huge and really just adds to the software spaghetti. But credit where credit is due: Microsoft is slowly getting the hang of this openness lark. (Via Ars Technica.)