Without any apparent warning, the Clear airport security program has shut down. The program set up special TSA checkpoints at airports it contracted with (PHL was NOT one of them) that were open onlhy to frequent travelers who registered and were vetted by TSA. It was supposed to speed up the wait, something that has been less of a problem recently because of falling airline traffic.
An announcement on the closing on Clear's Web site said its operator, Verified Identity Pass, had been unable to get financing to conntinue. A good blog post with personal observations and information can be found here.