We have not even released V1.009 to the internal testers yet so it will be a little while longer, it will be worth the wait though.
As for menus you can replace some of the screens already, I am not by my reloaded PC but I think they are in the titlesbank folder.
If you mean altering the layout of the menus for example buttons that is not possible yet and won't be for a while it isn't really a priority.
Windows 7 Pro, Intel i7 3.8 GHz, 16GB DDR3, NVIDIA GTX 780 4GB Superclocked