After Windows Phone 7 Series' grand unveiling at Barcelona's Mobile World Congress last month, Microsoft has circled back over the last several days during GDC and its own MIX10 conference to fill in many of the holes in this story -- in particular, details around the app development ecosystem and how third parties can take full advantage of it have been focal points. Of course, it makes sense: a modern smartphone is only as good as its software catalog, and Redmond's clearly keen to show that it knows how very true that is. XNA -- the technology that underpins Zune games and a host of Xbox content -- figures prominently int
