Google independently created sitemaps.org in an effort to universalize the sitemap usage among search engines. MSN and Yahoo! have taken to this and going to start supporting it.
Fourth place search engine Ask.com is not taking part in the standards process. Ask.com does not currently accept site maps submissions from webmasters.
I’m taking it that Ask.com doesn’t like us very much and doesn’t want to be very interactive. Google, Yahoo!, and MSN on the other hand, do want to be interactive and want to take feedback we can provide.
It takes a pro-active webmaster to be successful.

November 20th, 2006 at 4:55 pm
Uhm, don’t forget that Microsoft/MSN/Live.com (whatever) currently do not support Sitemaps at all (neither a text listing, nor the new-old XML standard). They’re aiming for 2007. When was the last time Microsoft hit a release date? Ask.com could still be faster in getting something actually released and working.
November 25th, 2006 at 12:41 pm
That’s not true.
read this blog entry
You’ll read that Microsoft definitely is supporting the sitemaps.org protocol.