Below is a rambling series of thoughts on the nature of the burden of proof in wikipedia. Pay it no heed, its here because I'll probably reuse one or two lines from it later.
Generally speaking on Wikipedia, the burden of proof is on the accuser or administrator to create sufficient reasoning to enforce editing restrictions on a user. We do so for various reasons, a liberal philosophical tradition and the way that a wiki works: To quote from Jimbo's user page "Newcomers are always to be welcomed. There must be no cabal, there must be no elite, there must be no hierarchy or structure which gets in the way of this openness to newcomers. Any security measures to be implemented to protect the community against real vandals (and there are real vandals, who are already starting to affect us), should be implemented on the model of "strict scrutiny." and "'You can edit this page right now' is a core guiding check on everything that we do. We must respect this principle as sacred."
The solutions thus far imposed generally speaking shift the burden to the user: "prove to us you're not a disruptive editor" or worse, go as far as to make the burden of proof completely unreasonable to bear, "prove to me you're a real human being with a skype account, prove to me you've got sufficient interest in this subject to edit Wikipedia for six months on other subjects and then come back to this one."
What I think would be within reasonable grounds is not shift the burden to the editor, but to lower the threshold for the accuser. There has been enough dramatic disruption on this subject where we can narrow the bounds of acceptable behavior to protect the interest of Wikipedia and the community as a whole, but we must do it carefully. "Removing the incentive for socking" is a noble, but ultimately unattainable goal. Instead I think administrators (those with with tools or without), should display considerably less tolerance for disruptive editing.