Man, been a while but i forgot how much i hate FreeBSD. Reminds me of the old days where solaris refused to ship their OS with a compiler or a decent shell, or require you to update /etc/nsswitch.conf to use DNS. Oh wait they still they do that with Solaris 10.. Ok, sorry tangent.
So if you need to compile mod_rails (aka passenger) on FreeBSD 7 with apache 2 and you used the default port install then you need to recompile with
and you will avoid that very nasty "Bus Error (core dumped)"
The other option is to use the Worker MPM and you should be good as well. I still cant mod_proxy to work but thats another issues.