Previously, the general interpretation of the Fifth Amendment was that the government could seize your land and compensate you for such things as highways, public buildings, elimination of blight, etc. Such things are often essential to the economy so the Fifth Amendment makes sense.
The suit before the court presented a different situation involving the government seizure of private property in the name of another private party. Meaning, the government can now seize your property in the name of a private developer who wants to build a mall, an office building, etc. Basically, if the new construction will provide tax revenue for the government, such a seizure is considered for the "public good" and more important than a private homeowner's rights.
So now, a rich private developer can grease his politician buddies and have you thrown off your land so he can build a Dairy Queen and nail salon.
Justice Sandra Day O'Connor had this to say in her dissenting opinion:
"Any property may now be taken for the benefit of another private party, but the fallout from this decision will not be random," O'Connor wrote. "The beneficiaries are likely to be those citizens with disproportionate influence and power in the political process, including large corporations and development firms."
I'm disgusted by the ruling and hope Justice Souter loses his home due to his own F'd up decision.