It's using a data feed from the Yahoo Developer network. The only data they have access to is inbound links (yahoo) so it's really only valuing the inbound link collateral associated with the domain name, rather than a whole business. Interesting info though.
Iain, the value fluctuates every 24 hours. Because UPMA has very few who are linked we dont have a huge value attached. Twenty four hours earlier we were value3e at just under $280. Link to us on your site and it will give us a tiny boost