Yes, SE's will crawl your site w/o a sitemap, but that's like saying that you don't need
a title or description meta tags - Google will pull your content to display on their results.
You don't need one, but like Temi said, you need one! If you want your site to gain in the
SERPs, and have the SEO edge over your competition - please use all the tools at a webmaster's
disposal
