Nokia and Microsoft are holding a joint press conference on the 5th of September 2012 in New York. Based on the invite I saw, it looks like Windows Phone 8 (with those tiles) event. Everyone is betting on Nokia Lumia Windows Phone 8 now.
Not sure what to expect but this might be the only chance that Nokia can really make an impact on their smartphones running on Windows Phone OSes. Maybe, we will be seeing this.
Actually, I am disappointed with the announcement of Windows Phone 7.8. Imagine buying a Nokia Lumia 800/900 and being told that none of these phones can be upgraded to Windows Phone 8.