You think because they squat in a public place that it then makes that public place their "home".
Amazing bit of fail on your part.
A home by definition does not have to be a structure with four walls, a window, and a door. Now this is fundemental to the constitution and the fourth amendment.
At present there are numerous cases that have been decided in regards to the issue. Google--read and learn.
In regards to Occupy Oakland for example the issue will surely come up. When the occupy-occupied Oscar Grant Plaza--their first eviction was illegal. Since their re-occupation of the plaza the Mayor allowed them to stay. Now she wants to remove them without due process. Oh, yeah...they have fourth admendment rights. Huge! Big!
In other occupy movements--many law suits have been filed by wonderful lawyers who claim the tenth amendment. The US Constitution is the supreme law of the land. Local codes stating once can not camp is superseded by the first amendment---redress your grievces to your gov and free speech and assembly.
Those tents are homes. And taking it away without due process process of law is unconstitutional. And cities that have not allowed people to put up tents and protest after 11:00pm are being sued.