I'm conflicted about this, so I will merely relate my contradictory impulses.
1. The protest has progressed without benefit of the usual apparatus of demands and signatories. Why change now? In the spirit of the Zizek speech, I have to think poetry rather than prose is what's working for them.
2. Groups coming to DC are just full of demands, and they don't amount to shit.
3. Once OWS starts concocting demands, the list becomes endless, effectively nullifying itself. Could this group democratically settle on, say, just three demands?
4. The encampment as the demonstration of an alternative society is thin gruel. It's wonderful that they are well-organized internally, but nobody thinks such an arrangement is sustainable, whether it's in Zucotti Park or on some prime agricultural land. Graeber has a good grip on the dynamics of protest and dissident occupation, but a weak grip on the salience of communal organization. Its greater power, IMO, is the nuisance value, the visibility, and constant flurry of activity (marches to assorted targets, civil disobedience) issuing therefrom.
5. Suppose they somehow worked up some cool demands. What then? They are still sitting on their arse in the freakin park. Come to D.C.? Camp out in some other park? Join the Green Party?