The case in question was about a developer who claimed he could generate more tax revenue for local government with a particular piece of land, except the landholder wasn't selling. The Supreme Court has effectively ruled that increased tax revenue is a legitimate point of "public interest"; as such, governments can take your property and give it to other people who promise to pay more taxes than you do.
I'm so mad I can't see straight.
UPDATE: Here's a link with a good overview from AP News MyWay.
UPDATE: Another overview from the NY Times.