I've only had the chance to skim the opinion, and I will be heading off to an all day practice Multistate Bar Exam in just a few minutes, but I thought that the second-to-last paragraph of the opinion was particularly notable:
Modern cell phones are not just another technological convenience. With all they contain and all they may reveal, they hold for many Americans “the privacies of life,” Boyd, supra, at 630. The fact that technology now allows an individual to carry such information in his hand does not make the information any less worthy of the protection for which the Founders fought. Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple—get a warrant.This is an extremely important opinion, both in terms of the practical effect it will have on law enforcement practices and what it may signal regarding the Court's willingness to apply constitutional protection to people's digital information in future cases.
UPDATE: I've updated the title of this post