The decision is troubling to me, but I have to admit that the precedence of remote surveillance not needing warrant is legally accurate. In this case I would say it is the law, not the courts, at fault. Even without using GPS, movement can be tracked in any city using traffic control cameras, parking security cameras, toll stations cameras, etc.
Until (relatively) recent developments in technology, remote surveillance involved a significant amount of resources. As such, the use of limited resources was, by sheer necessity and without the need of additional oversight or regulation, limited to specified suspects of crimes under investigation. But modern technology allows the use of random and wide spread remote surveillance without overstretching limited resources. And there in lies the problem - as having available relatively unlimited surveillance resources opens up the means to abuse. As such, it needs to be regulated - meaning new laws - or even new constitutional protections - need to be written.
A good start would be for the people of each state to amend their state constitutions to add movement as a protected aspect of privacy. Using a court decision to add movement as an aspect of privacy would be, IMO, inadequate, for unless it is added to the actual language of the Constitution, it only takes a contrary court decision at a later time to take it away again. If we actually add it to our constitutions (start with the states because it is easier and can be accomplished through direct legislation) then it will take another amendment to take it away again - which a WAY less likely than a court reversal.
Addendum: of note is the state of Montana has taken a first step in addressing the issue of remote surveillance through technology by outlawing traffic light cameras.