Forum OpenACS Q&A: Re: Two interfaces and one service to bind them all?
1) Start the services with the ip 0.0.0.0 which would force them to accept incoming connections on all interfaces. This does not always work on windows machines. For example with AOLserver on windoze I had to prebind it to multiple IP addresses on each machine using command line options.
2) Alternatively you could forget about assigning two static dhcp adresses and bridge the interfaces. Brigding would bind the two interfaces into one logical interface with one ip address. Start your services on this ip and both wifi and ether can connect to them. Bridging is available on linux and on Windows XP pro. I don't know about the others. see bridge.sourceforge.net for a linux explanation.
I would use the second option. It has much more expandability, and easier to setup then 1 (if you are running linux - 3 commands).