I don't think I have these sitemap url's published anywhere publicly accessible for search engines to crawl and discover (I've just been submitting them to Yahoo and Google directly) so I thought I'd put them in a post --

http://www.mapforums.com/sitemap.txt.gz
http://www.mapforums.com/sitemap_1.xml.gz
http://www.mapforums.com/sitemap_index.xml.gz

Although Yahoo and Google know about them, it is the smaller search engines I haven't submitted to that might find them now..

By the way, I did find this advice for trying to submit a sitemap to MSN, instead submit to MoreOver.com and it will show up in MSN's index.

You do this with a ping like below where you change the url at the end to your sitemap url..
http://api.moreover.com/ping?u=http:...p_index.xml.gz

For the Ask search engine the "ping" statement is like --
http://submissions.ask.com/ping?site...temap_1.xml.gz

Note that many search engines now look for a line like this in your robots.txt file so this is also good practice --

SITEMAP: http://www.mapforums.com/sitemap_1.xml.gz

I think put the sitemap xml address in the robots.txt is more convenient.

i.e.sitemap:http://www.mysite.com/sitemap.xml