The Peace prize is one of the easier arguments. The beneficial affect on the lives of everyone, and the egalitarian nature of editorial review is clear.
The Literature prize could be awarded for creating one of the most important literary works in history. The prize itself was to be awarded to the "person who shall have produced in the field of literature the most outstanding work in an ideal direction." The committee has almost always given this as a lifetime achievement award in fiction and poetry, but there have been notable exceptions. Both Winston Churchill and Theodor Mommsem were awarded for their historical works. The artistic community which controls the prize is perhaps too elitist to award the egalitarian work of Wikipedia.
The Economics prize is the most interesting. I do not know of any precedent for non-theoretical work. But the value of Wikipeida to the economics field is in creating an entirely open, non-monetary market. This should be a great tool for economics, and is ripe for discovery.
I would, however, support the first Nobel Prize award to a conglomeration of people: the editors of Wikipedia.
Note the exception that "The Nobel Peace Prize may also be awarded to institutions and associations." - http://www.nobelprize.org/nobel_organizations/nobelfoundatio...
The award may not be given to one person and the funds to an organization: "On the Festival Day of the Foundation, December 10, which is the anniversary of the death of the testator, the prize-awarding bodies shall present to each prizewinner a check for the amount of the prize, a diploma and a gold medal bearing the image of the testator and an appropriate inscription." - http://www.nobelprize.org/nobel_organizations/nobelfoundatio...
Also, very few of the editors of Wikipedia are members of the Wikipedia Foundation.
Other than these few rules, it wouldn't be a problem. Just need to amend the rules. :) http://www.nobelprize.org/nobel_organizations/nobelfoundatio... .