I have built Qt 5.0.1 statically in VS 2010 under Windows 7 x64. The configuration parameters were
configure -debug-and-release -opensource -confirm-license
It's a Qt platform plugin issue. Using qt.conf resolved the problem for me on MacOS. It doesn't matter if you link Qt staticly on not.
I tried to staticly link to libqcocoa.a (or qwindows.lib) without success. I will let you know if i succeed.