That was yesterday, this is today. Demonstrators, encouraged by their success, will be going for bigger effects. Police around the country will be getting out their mace, tear gas, and stun guns. And those little black objects on their belts can propel lead pellets over large distances.
A protest lets you show support for peace. A mob makes your cause look ugly--and mobs are dangerous. When police are angry and scared, bad things can happen. Being arrested by an angry cop, in company with a lot of other people who are excited and scared, is much more scary than exciting. OTOH, nasty as it is, it is more fun than being crushed or trampled by a mob running away from tear gas. If you go to a protest, stay far from the "center" of action.
Better yet, stay home and sign up to work for an anti war Democrat like Howard Dean. That would bring us closer to sane government than we are now.
Democratic candidates in order of how much I like them and why
Anti-war: Howard Dean, Dennis Kucinich
Voted last fall to authorize Bush but says he's against *this* war: John Kerry
No chance to win: Bob Graham, Carol Mosely Braun, Al Sharpton, Gary Hart
Pro-war: John Edwards, Dick Gephardt, Joe Lieberman