I have been working on this application for some time now. The idea is very much similar to what Vivek Ramachandran and Sukumar Nandi mentioned in their patent-pending Detecting ARP Spoofing: An Active Technique paper.
The application, "arp-secur", uses some basic scanning techniques to conclude the authenticity of a MAC-IP pair. It has been developed on an IA64 based Fedora 14 installation. It requires root privileges so as to be able to sniff and inject datalink frames.