Samuel Alito says what we've all been thinking: You know, I don’t know what society expects, and I think it’s changing. Technology is changing people’s expectations of privacy. Suppose we look forward 10 years, and maybe 10 years from now, 90 percent of the population will be using social networking sites and they will have on average 500 friends and they will have allowed their friends to monitor their location 24 hours a day, 365 days a year, through the use of their cell phones. Then — what would the expectation of privacy be then?
I don't think its logical to conclude that its OK for the police to install a tracker on your person without a warrant just because lots of people do so willingly, but there is a stronger argument that the police might not need a warrant to access data if you are one of the ones who has done so willingly. I think the key question is how widely you're sharing that data. There are some odd moments in the linked article. It says: The Supreme Court first created the standard of “reasonableness” in the context of the Fourth Amendment in 1967.
That is simply not correct. Also it includes a quote from Scalia which is so bizarre that I suspect that it could not accurately reflect what was said in the court room: Justice Antonin Scalia replied moments later that the police “can do a lot of stuff that is unreasonable under the Fourth Amendment.”
No, they can't. That is pretty much the whole point of the 4th Amendment. I think Scalia knows that. Supreme Court, Help! My Mini-Bar Is Spying Without Warrants | Threat Level | Wired.com | 
