So it's 2:56 in the AM and I've just hacked up a little app to enable moving up a directory in Windows Explorer by using the Thunar middle click + drag up gesture. You can find it at ZaneA/Win32-Hacks.

Enjoy.

Edit: This morning I've extended it to have left and right gestures to go backward and forward respectively just like Thunar and Nautilus. Down is used for exit rather than refresh as Windows seems to take care of this.