Does that mean it's viewpoint discrimination, which is what some Tea Partiers are insinuating?
I raised this question during the Wisconsin protests, as we saw the police do all sorts of things to yield to the protesters. For example, they would respond to impromptu marches around the Capitol by blocking regular traffic. We talked to the police who were carrying out that policy — I have video — and they explained that it was the best way to deal with crowds that size. That is, it's not viewpoint discrimination, but a neutral response designed to maintain the best semblance of order when the police are outnumbered.
I tried to needle them with law professor questions — I do random acts of law teaching around town — about whether they'd treat Nazis or some such loathed group the same way. The crafty but troubling answer was: The Nazis would never arrive in such numbers.
The first link, above, is via Instapundit, who attributed Boston's special treatment of the Occupy Boston protesters to the fact that "the officials are Democratic hacks, and the 'protesters' are Democratic tools. Duh."