They've been successful. The place really is clean, even with people sleeping there overnight.
A lot of the organization is on the TAA level. Here's a post on the TAA blog about "Teach-out Tuesday":
Membership of the Teaching Assistants’ Association voted today [Feb. 20, 2011] to call for another “teach-out” on Tuesday, to protest the reconvening of the State Assembly and Governor Scott Walker’s planned statement about his budget....
We are calling for a teach-out rather than a walk-out because we do not want learning to cease at the UW. We value education and thus we are calling for instructors to use their discretion to cancel classes, reschedule them or hold them off campus. We are calling on action from teaching assistants, research assistants, project assistants and professors.