"In moving away from our decisions sanctioning the condemnation of harmful property use, the Court today significantly expands the meaning of public use. It holds that the sovereign may take private property currently put to ordinary private use, and give it over for new, ordinary private use, so long as the new use is predicted to generate some secondary benefit for the public–such as increased tax revenue, more jobs, maybe even aesthetic pleasure. But nearly any lawful use of real private property can be said to generate some incidental benefit to the public. Thus, if predicted (or even guaranteed) positive side-effects are enough to render transfer from one private party to another constitutional, then the words “for public use” do not realistically exclude any takings, and thus do not exert any constraint on the eminent domain power." -- Justice O'Conner

Associated links:
http://www.worldchanging.com/archives/002951.html
Opinion: http://straylight.law.cornell.edu/supct/html/04-108.ZO.html
Dissent: http://straylight.law.cornell.edu/supct/html/04-108.ZD.html