Look at how clear the sign is compared to the background and people...they look fuzzy/washed out....but not the sign.
Yeah, I was just poking around the source site, and I'm not sure what to make of it yet. May well be a fake, because I'd be surprised if even the unwashed anti-war freaks would let that hateful message stay up.
However, having been at a few of these rallies (as a counterprotester), I have seen some disgraceful signs and people right in the middle of the crowd.
http://users.lmi.net/zombie/sf_rally_march_20_2004/anti-american/
It's the real deal. I was at that rally, and I got a picture of this same scumbag too. FREEPMail me if you want an alternate view to compare.