This article will explain the decision without all the legal talk.
http://www.forbes.com/feeds/ap/2007/06/28/ap3867730.html
The courts thinking, is pretty much what festool has said. They don't want people to shop for price, they want people to shop for customer service. The court views this type of activity part of the companies marketing strategy and thus want to give them the freedom to compete as they see fit rather than the government. As others have said, this does not allow companies to collude, that is completely illegal. I think the crying wolf on the part of Justice Breyer and others is just that. Companies that have minimum price agreement are unique and their products must have significant value (not monetary) to consumers if they are willing to pay the higher price. So companies like Festool, Leigh, Kreg Tools, etc. could have such agreements and not suffer lower sales. Companies like Dewalt, Milwaukee, etc. would have a much harder time considering their products and how they make money (volume sales).
One interesting part of the decision seems like it could affect Festool's Domino. Depending on how you determine what the domino does, i.e. does anything else legally do what the domino does. Despite what Festool says in its marketing, I think in those court arguments, they would say that the biscuit joiner, pocket screws, multi router, etc. fit the tool category and keep the domino from being a singular product. I would take the quote below differently, as I think a court would.
"Moreover, if only one brand is available, retailers and consumers can still sue manufacturers for anticompetitive conduct, Englert said. The courts will now evaluate such suits on the merits, rather than automatically finding them illegal."
Herr Doktor Festool will not just roll over and play dead.