I don't think we will see New Windows soon...
Vista still has too many things to improve.
I can't remember how many years was between first XP release and first Vista release.. I remember Windows 95, then 98, then Millenium (2000) and XP.. I guess it was 2002. Vista was released in 2007, right? So we have 5 years between XP and Vista releases. Then we should wait for New Windows not earlier than 2012 I suppose...
About name..Let it be Windows Nano!