Created attachment 289787 [details, diff] xorg-drivers-1.11.ebuild.diff The virtualbox people removed their special mouse driver with the virtualbox-4.1.4 release. Bug #386741 was filed to remove the x11-drivers/xf86-input-virtualbox-4.1.4 (which I committed before testing the package thoroughly) but when some user still has INPUT_DEVICES="virtualbox" set he will still get pulled the now obsolete xf86-input-virtualbox package. Please remove the dependency. The attached patch shows what should be sufficient.
Fixed in CVS.