Microsoft has confirmed Windows Blue as a codename but otherwise isn't saying much about it. New screenshots doing the rounds suggest that it will carry a Windows 8.1 version number, and that may well end up being the official branding as well.
Screenshots on Winforum.eu shows the Windows 8.1 version number. Veteran Microsoft watcher Mary Jo Foley also reports that Windows 8.1 will be the official name, though this will be subservient to the main Windows 8 brand. That makes sense: having only launched Windows 8 last year, Microsoft wouldn't want to ditch the brand so quickly.