It's not unusual for "reality" show contestants to turn up on TV again and again. But how many of them wind up up at PBS? Yul Kwon, the communications lawyer who won CBS' "Survivor: Cook Islands," will host a four-part series, "America Revealed," next fall on PBS, the network announced Sunday. The show, based on a BBC series called "Britain From Above," uses aerial footage and information from satellites circling overhead to look at the systems that keep the country moving far below. Not exactly the kind of show where I'd expect to find "Boston Rob" Mariano or Omarosa, anyway.