If they are left to their own devices they might show up at the Democrat and Republican conventions. It might be '68 all over again. Which only bodes well for the Republicans.
Except at RNC08 the protestors were assembling incendiary devices. Factor in as well potential infiltration by Islamofacist types, but then any use of a weapon will immediately be pinned on the Right (re: Moonbats still think Jared Loughner was getting dog whistle commands from Sarah Palin when he shot Congresswoman Giffords).
2012 will be a violent year. When the Left finally realizes they are losing, they will look to take it down in one last temper tantrum.
One might reasonably conclude that the protesters are incompetent but useful idiots. It would be unwise to make that assumption about the protest organizers.
Violent suppression of conservative political opponents has already occurred in other venues [c.f Louisiana, Saint Louis, Los Angeles). The Left is very good at organized activities - including violent ones. The Government in most areas is heavily influenced by Leftists now, and is inclined to give such events a pass.
Feeling armed and righteous is an insufficient plan. Being part of the majority is also insufficient.
The faction that is best organized and supplied usually determines the outcome of any dispute.