For those of you who have not read the MMO Champion article, the gist of the matter is that, currently, effective heals from Judgement of Light give threat to the Paladin who cast it. This means that on fights where there is significant raid damage, Paladin tanks who use JoL get enormous amounts of burst threat. In contrast, if any other Paladin (say, Retribution, whose JoL is much more powerful) uses it instead, they get huge amounts of threat, enough to risk pulling off the tank.
To abate this issue, Blizzard is removing threat from the JoL heal.
Note that there is apparently a separate problem where, with multiple Paladins Judging Light/Wisdom, Holy Paladins may not be properly benefitting from their talented haste effect.