app-emulation/virtualbox-bin-3.2.6 doesn't support Python 2.7.
The ebuild now supports installation of a python-2.7 module if one is provided by upstream. I have talked with upstream and they will ship such module when there are python-2.7 packages available for their build machines.
This bug should be left open until upstream fixes it.
Fixed with virtualbox-bin-3.2.8