There is no official word just yet. Until the Judgement page on the Wizards site comes out in June or late May, there won't be an official word. So the exact implications are yet to be seen in tournaments. There is a general idea, however, that they will allow you to search from your sideboard or the removed-from-game pile.
The general word about them ranges from "Oh my God, what were they thinking" to "So they're limited-power Rings of Ma'ruf" to "Cooooool."
As the owner of a single Ring of Ma'ruf, and having used said artifact in casual play, I can tell you what's been accepted in my group. You can get any Magic card you want (in this case up to the limits of the particular Wish) except for those with the word "ante" on them. That includes additional copies of normally restricted cards (I've grabbed an extra Mind Twist in my time) and cards that belong to your friends that they aren't using at the time (this one is the most fun application, IMHO).
They'll be the ultimate casual play cards. I know I'll use them if I get any.