Sharing one IP address among multiple Apple devices Is it possible to share one IP address between two Apple laptops (both running Snow Leopard in my case) so that both devices can connect to the internet?
Yes, but with caveats.

MacOS X has an "internet sharing" mode in the "Sharing" control panel, but you have to use different network interfaces for the "internet facing" and "internal facing" sides of your network.

So if you're connected to the Internet over your ethernet port, you can share your connection to WiFi clients.  What you can't do is connect and share over the same port.