Or you can just add a line to your robots.txt. That's what most people do if you haven't got a vast site. (What is it again, up to 50,000 per file?)
Obligatory reminder: If all your pages can be found by simply following ordinary links (including javascript, assuming Google is allowed to crawl scripts), you do not need a sitemap. If all your pages can not be found by following ordinary links, you may have bigger problems than the lack of a sitemap.
