I can't find a better description of this, so I'm stretching fair use a bit to give you the whole blog post from Salon. You can click on a day pass to see it on their site.

Fernando Suarez del Solar wasn't very political before his son, a 20-year-old marine named Jesus, was killed in Iraq last year. Since then, though, the 48-year-old has left his job to spend all his time agitating against the war, and last night, he took his message to Madison Square Garden.

A friend lent him a media pass, and at around 9 p.m., as Arnold Schwarzenegger began speaking, he unfurled a three-foot-wide sign with his son's picture and the words "Bush lied, my son died."

A group of delegates immediately called security, which ushered him into Madison Square Garden's lobby. There, he says, he gave a few interviews while some passing Republicans jeered, saying, "Get out of here. You're unpatriotic." More security showed up, including members of the FBI and the Secret Service. "I say to them, 'I pay with my son's life for my freedom of speech, but you can arrest me, it's OK.' The police said, 'no sir.'"

"The surprise for me," says del Solar, "is some people, Republican people, say to me, 'I'm sorry for your loss, you are right.' About seven, eight persons say, 'I am Republican, but you are correct, this war is not necessary.'"

Here is another article about the same protest. When people filed out after watching Schwartzenegger's speech, he was still in the lobby with his sign.

As delegates, fresh from Schwartzenegger's pro-Bush speech, marched into the comparatively fresh air, they were greeted by Fernando Suarez del Solar, who silently held a pink sign showing a young man's face and the reading, "Bush Lied, My Son Died," Suarez's son Jesus was killed in battle on March 27, 2003, at the age of 20. His was one of the first fighting deaths of the war. Fernando Suarez, who traveled from San Diego to protest the war in Iraq, encountered few problems while making his statement. "Most people don't say nothing. Some people say, 'I'm sorry.' Only one person has said 'Get Out of Here.' People give me respect." Suarez and his pink-clad protest partner Nancy Mancias eventually attracted the attention of security, who circled the two and began questioning them on the specifics of their press credentials. At that moment, a member of a Spanish language television network claimed the two as part of their network and escorted them upstairs to be interviewed. After the interview, security escorted Suarez and Mancias out of Madison Square Garden.