Google Sitemaps is an experiment by Google to improve the web for webmasters and users. First of all you create a sitemap - either manually (Sitemap Protocol), or via a tool you install on your server (Sitemap Generator).
Sitemap Generator requires Python 2.2 or higher installed on the server. If you cannot get Python installed on the server (i.e. using hosting solution with Windows and/or host unwilling to install extra software), you could always install/run it on you local development machine, then upload the generated sitemap. Since Sitemap Generator is open source, anyone can improve it - SourceForge Project: Sitemap Generator.
This is also open to other search engine developer as it is under the Attribution/Share Alike Creative Commons license (i.e. can be used commercially, but must give author credit and share any changes you make). Sitemap Generator uses the BSD license (the Creative Commons license refers to the protocol, not the tool).