The reason is apparently: enewuser vboxguest -1 /bin/sh /var/run/vboxguest vboxguest This conflicts with the policy of only creating directories in /var/run on demand. As far as I can tell, the service doesn't use that directory, but didn't check thoroughly. If it is not needed, /dev/null can be used in enewuser instead. If it is needed, I guess that the proper location is /var/lib.
+*virtualbox-guest-additions-4.2.6 (22 Dec 2012) +*virtualbox-guest-additions-4.1.24 (22 Dec 2012) + + 22 Dec 2012; Lars Wendler <polynomial-c@gentoo.org> + virtualbox-guest-additions-4.1.22.ebuild, + +virtualbox-guest-additions-4.1.24.ebuild, + -virtualbox-guest-additions-4.2.2.ebuild, + virtualbox-guest-additions-4.2.4.ebuild, + +virtualbox-guest-additions-4.2.6.ebuild: + Version bump. Removed old. Don't create /var/run/vboxguest (bug #401029). +