The issue resolved in City of Ontario v. Quon was whether a police officer's Fourth Amendment rights were violated when his employer, the police department, reviewed text messages on his pager for legitimate business reasons. The Court held that the search was reasonable.
While criminal law is not my forte, this case has potentially enormous significance for privilege in electronic communications. At this time, a wave of cases addressing whether e-mails sent from an e-mail account maintained at a business where that business as an enforceable policy providing that personal e-mails are monitored and not confidential can, nonetheless, be claimed as privileged. Although the issue typically arises in employee-employer litigation, where the employer wants access to e-mails sent from the employee to his lawyer, the principle that privilege is waived would apply where a third-party seeks access as well.
Quon will likely influence this body of law, as well. Although the court mentioned that this was not as intrusive as monitoring his personal e-mail, it did not address e-mail sent from a business account. Stay tuned, and be careful!