Blizzard has updated their UI developement policy granting a grace period to the UI addon community to comply.  Those who do not comply after May 19 will be contacted by the infamous Blizzard Legal Department.  A letter you really won’t want to ever have in your inbox, no doubt.  Blizzard is known to win most if not all of their cases in court.  This policy was triggered when certain addon communities were selling the addons or advertising within World of Warcraft through the UI system.

Blizzard Quote:
Nethaera: On March 20, we released the new add-on development policy to the public as an ongoing effort to help ensure add-on integrity, safety, and quality for the community. Since that time we have been in touch with many UI development communities on what the policy means to them and the continuing development of these add-ons. We would like to announce further that we are providing a sixty-day grace period beginning at the time of the initial release of the policy for UI developers to comply with the new policy. After May 19th, Blizzard Entertainment will begin to enforce the Add-on Development policy, and developers found to be in violation of this policy will be contacted directly.—source