In ages past, the "eminent domain" clause has been used to seize property for public use – such as roads or schools. However, there is a big difference between "Public Use" and "Public Benefit". This ruling makes the two terms synonymous. The dissent, written by Justice Sandra Day O'Connor, was particularly stinging.
In plain English, this means that the local government can raze your house if they think that they can get more "public" income (i.e., taxes) by putting a Wal-Mart there.