i actually think the ruling is much narrower than the media is reporting. the court seems to say that the police department would have been all set if it had stuck with its formal policy. if it had, the employee wouldn't have had an expectation of privacy. but a lieutenant had his own informal policy that said text messages wouldn't be checked unless the officers refused to pay for the overage charges. that's what undercut the formal policy.
also i think attaining the numbers dialed on an employee's mobile phone won't be a problem since the court said phone numbers aren't protected. from what i can tell, if the police department just got the phone numbers dialed using the text messager it would have been in the clear. instead the police department got the content of the messages.
http://www.ca9.uscourts.gov/ca9/newopinions.nsf/D2CDDB4098D7AFB28825746C0048ED24/$file/0755282.pdf?openelement