Medary.com

Here come the demonstrations:

When thousands of Iraq war protesters gather in Washington Saturday, their chants and amplified speeches are likely to be heard inside the secure grounds of the White House where the commander in chief has made his case for sending more troops into combat.
. . .
House Speaker Nancy Pelosi is the main political target. War protesters want something tougher than nonbinding resolutions opposing the "surge" in additional US forces. Some want hearings on the controversial basis for the war itself, perhaps leading to the impeachment of President Bush.

It's not just the nation's capital, where busloads of people from at least 30 states are headed to make their voices heard.

Oddly enough, organizers are going out of their way to remain anonymous (as stated later in the Christian Science Monitor story linked above).  Why would that be?  Perhaps an agenda being hidden?

Word of the day:  Astroturfing.
(from Wikipedia):

In politics and advertising, the term astroturfing describes formal public relations (PR) campaigns which seek to create the impression of being a spontaneous, grassroots behavior. Hence the reference to the "AstroTurf" (artificial grass) is a metaphor to indicate "fake grassroots" support.

The goal of such campaign is to disguise the agenda of a client as an independent public reaction to some political entity —a politician, political group, product, service, event. Astroturfers attempt to orchestrate the actions of apparently diverse and geographically distributed individuals, by both overt ("outreach," "awareness," etc.) and covert (disinformation) means. Astroturfing may be undertaken by anything from an individual pushing their own personal agenda through to highly organised professional groups with financial backing from large corporations.

Do I have evidence that the anti-war demonstrations are astroturfed?  No.  Is it the standard mode of operation of leftist activists?  Yes.