I noticed these in our logs:
Sat Jan 12 15:56:45 2013 Note: cannot open /var/run/openvpn/ifconfig-pool-persist for READ/WRITE
A `mkdir /var/run/openvpn` as root is all it took to fix it. The error appears upon starting openvpn.
For what it's worth, this also happens on a fresh install so it should be easy to reproduce.
This isn't a problem with OpenVPN within Gentoo but how you're using it.
The use of the --ifconfig-pool-persist file is *not* at default, and not something Gentoo is adding in the initscript. The only use the initscript provided by Gentoo has with /var/run/ is to store the PID, and that's stored at /var/run/ (not an openvpn subdirectory.) Thus /var/run/openvpn/ is *not* expected to exist on a "stock" install.
You are the one that has specified the path argument to this file, and it is thus your responsibility to insure that the directory exists where you want this file to reside.
And finally, while this isn't on topic with your original bug, you're better off not even using the --ifconfig-pool-persist directive anyway; it won't give clients static addresses since the client -> IP mappings are used as suggestions only by openvpn. If you want proper static IPs with openvpn, use a smaller --ifconfig-pool range and use --ifconfig-push directives in a ccd or --client-connect script.
Since this is not a bug with OpenVPN or Gentoo, I suggest it be closed out.
Sounds good. Josh, thanks for the analysis.