A quick Per Curiam order explains that the challenge to the NSA's bulk telephony metadata collection is not moot.
Beyond that, it seems Circuit Judge Janice Rogers Brown and Senior Circuit Judge Stephen Williams conclude (in separate opinions) that the plaintiffs fail to satisfy preliminary injunction standards, and neither finds a standing problem on the present record. (Only Judge Brown thinks plaintiffs meet standing's minimal requirements at this stage of the case—"barely.") The pair thus vote to send the lawsuit back to the lower court. A readers know, the latter earlier had concluded that the NSA's bulk metadata program was likely unconstitutional, and entered (yet simultaneously stayed) a preliminary injunction against the program's continued operation.
Senior Circuit Judge David Sentelle dissents; he would simply dismiss the suit outright, reasoning that plaintiffs do lack standing, period; and that federal courts have no jurisdiction for further proceedings as to whether plaintiffs nevertheless might establish their standing.