Nothing! PIT and PHL are just overstaffed in NOV, so they are offering a VPLOA (voluntary personal leave of absence). This is normal operation for this time of year. It happens every year.
There were alittle over 140 f/as that took the VISP (only 4 active). Also, there are 333 f/as (out of almost 1,000) summited to come back in Dec 2005. Historically, only about half of those will actually do it. They were up against a deadline so they said they would return.