> My first guess is the lack of proxy ARP on all but the IP on the
> Fedora server that works.

I've got entries there for both

> If that isn't it, what happens when you assign the Fedora box to a
> different IP, and assign the Fedora box's public IP to the Centos box?

You hit it. It's a problem with the IP not the server. Now the CENTOS  
server is visible and the fedora box is has no access. Tomorrow I  
will sort through my configurations with fresh eyes and see what I  
can find.

Thanks for the suggestion!
-marc