Support engineer "Zeeshan" pointed my attention to this Team Blog: http://blogs.msdn.com/b/nav/archive/2013/01/28/microsoft-dynamics-nav-2013-compatiblity-with-microsoft-windows-8-and-microsoft-windows-server-2013.aspx.
I just decided to "copy" the blog to give it somewhat more attention ;-).
Note that Microsoft has finished the procedure to be able to say that both Microsoft Dynamics NAV 2009 R2 and Microsoft Dynamics NAV 2013 are compatible with Microsoft Windows Server 2012 and Microsoft Windows 8.
Ps, here you can find the complete System Requirements for Microsoft Dynamics NAV 2013.
Is NAV 2013 compatible with Windows 8.1 (Build 9431) ??