Part of the problem with hockey on TV is that flying pucks
    move so quickly they are almost invisible to the at-home
    viewer. Honey proposed digitally inserting a blue glow
    around the puck that would lengthen into a contrail whenever
    it was moving faster than the eye could see.

Funny, the first place I ever read about this was in Wired in the mid-90s. I think they called it "pucktrax." There's virtually no mention of it online anymore, except for a handful of snarky forum posts deriding Fox's use of a "gaudy blue flame."

see: http://www.tribalwar.com/forums/archive/t-606021-p-37.html, among other places.