Sigh, I fear I can't help at all, and that is aggravating because I thought I was good at fixing vpnc problems. (Although not at reading strace--I'm not sure how that works, but I think there's a problem with adding files as well as size limits. I THINK--I'm not sure about that, and sigh, you would think as a CM, I would know the forum rules.
OK, back to this issue.
Did you install using yum, or the source code? If the source code, is it at all worth trying to uninstall, and trying with yum? I've now tried on two F11 boxes and everything is just working.
(One 64 bit, one 32 bit.)
I'm sorry I can't be of more help save to blithely say it works for me.