Actually, the Glow Pucks are still there; they simply operate differently. To enable precise tracking of the puck by rafter-mounted detectors, the LEDs in the pucks had to be run far above their ratings, and this resulted in a very short operational life. Consequently, these LEDs quickly became DEDs (dark emitting diodes - see
http://www.hfunderground.com/board/index.php/topic,7051.0.html). The engineers quickly realized that they had the whole design paradigm ass-backwards. Instead of tracking an illuminated puck, it would be far easier to track the dark of an ice cold chunk of black rubber.
As soon as all the detectors are converted to Dark Detectors we will all be able to enjoy Fox Trails once again.