Awesome hack! It's, unfortunately, only a matter of time before Google shuts this guy down. Google, do the right thing and have an option to display Page Rank on your search pages.
A fellow by the name of Stephen Morrison has hacked up "Proogle," a Google skin that returns Google's results but adds in PageRank scores. The site is linked to what I presume is Stephen's home site, Webmaster Brain" (no contact info on his site, but a number of neat tools are there, including a link popularity tester).
I'm told Proogle has gotten quite popular among the webmaster community, as a result, I'll wager won't be up for long - it more likely than not generates more than 1000 searches a day, a violation of Google's terms of service. (The site even implores: "Google, Please Don't Sue!") This is yet another example of interesting hacks built on top of Google that, in the end, will probably end up on the dustbin due to popularity. Another recent example is Social Grid. I did hear back from the fellow behind that site, who admits he has yet to "ask permission" to build on top of Google. His credo: Code now, ask for forgiveness later.