What state are you posting from? Check state laws on photographs of public events and see if you find anything. I found this:
http://pcworld.about.com/news/Jun062006id125893.htm
Taking Pictures of Public Events
Q: Do I need a permit to photograph a public event or in a public place?
A: No. It's your constitutional right to photograph in public
Photographing People in Public
Q: Can I photograph people in public places without their permission?
A: Absolutely. People get really muddled about this issue, but the
reality is that you have a virtually unrestricted right to use a camera in public. One big caveat: It's common courtesy to get verbal permission. Nonetheless, people don't have the right to bar you from photographing them in public, where they would not ordinarily have an expectation of privacy.
Q: Can I publish pictures of people I've photographed without permission?
A: That depends upon the purpose of the picture. If it's artistic or editorial in nature, or can be characterized as to inform or educate, then you do not need your subject's explicit permission.
If the picture or any associated text may be libelous, defamatory, or fall outside of what courts have described as "the normal sensibilities" of the target audience, then you may need permission from the subject for your own protection. You also need permission from the subject if the picture is used for commercial purposes, such as in an advertisement.
Q: Why is the subject's permission required for commercial photos?
A: You need to get permission from the subjects of your photos when you're creating images for commercial purposes because their role implies that they endorse the product. If you photograph a mother and baby in a local park, for instance, and the image ends up on a Web site selling baby food, then it implies that the people use the product--or at the very least endorse it. And that's the difference between commercial photography and publishing candid photos of strangers in a photo gallery, in a magazine article, or on the Internet. In those cases there's no kind of product endorsement implied.
Q: How do I get permission from my subject?
A: You'll do that with what is called a "model release form." Someone you've photographed, or plan to, signs this document, giving you permission to publish their image. You generally only need permission from the subject of your picture if the image will be used for commercial purposes (advertising). There's no official format for a model release. You can make your own, and there are many good examples all over the Web. In fact, here's one you could download, print, and carry around in your camera bag.