Last month, Blizzard released a new add-on development policy. There were several contentious points in it; notably, authors can no longer charge money for add-ons, nor can they solicit donations in-game (asking for donations on web sites is still OK). In-game advertising is also not allowed.
In the wake of the announcement, the authors of several popular mods announced that they would no longer be developing and/or distributing their addons, while other addons (Carbonite being a notable example) are switching to an entirely free model.
The news today is that Blizzard is giving a 60-day grace period for developers to comply with the new model.