The Supreme Court has granted certiorari regaarding a federal appeals court in California that reading text messages sent on devices provided by the employer violated the worker's privacy rights and amounted to an "unreasonable search" barred by the U.S. Constitution. The case is City of Ontario v. Quon, 08-1332.
The city appealed to the Supreme Court, saying employers typically have policies in place establishing that workers have no expectation of privacy in electronic communications on employer-owned equipment.
The PDF opinion may be found here.
Source here.