Here's the meta description for sitemaps.org:
"The Sitemaps protocol enables webmasters to information earch engine about pages on their site that are available for crawling."

Search for sitemaps and look at the 3rd result:
http://www.google.com/search?q=sitemaps&ie=utf-8&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a

Who would visit this site supported by Google, Yahoo!, and Microsoft?

It's worth mentioning that the site was created using Yahoo Geocities.

Well, if the three big ones get together and start linking to this site, and mainstream reports and blog articles point to it when mentioning the news, it's almost naturally going to rise to the top... another question might be, what do people actually look for when they enter "sitemaps" into Google? I mean we know what they want when they enter [how to create a sitemap] or [sitemap visualization tool] or [history of web sitemaps] or something, but single words are often harder to disambiguate...

I was just saying the text is poorly written.

.... enables webmasters TO INFORMATION EARCH engine about ...

and that's not very professional for a site supported by Google, Yahoo, Microsoft.

Completely misunderstood you there...
Well, it's a spelling error, but I can't find an easy contact button on Sitemaps.org, so their bad :)

I agree to Philipp, almost all visitors search "Sitemaps" for easy usage tools.
Only very very few persons like me like to research it.
I think I almost already touched the ege of the truth. But endless new ideas tell me that it is not the final.