There are other metrics that people will have to start paying attention to, and this is just a reminder of that. Relying on PR has been a crippling thing for many people, and it's tended to be the main (or only) factor that "mattered".
However if you like to put a number on a domain, SEOmoz' factors such as mozRank and Domain Authority can fill that void. Personally I do like to check out sites using SEOmoz OSE (when purchasing a domain or working out a reciprocal link deal for instance).