Wikipedia is now using (Google) Sitemaps for about a year and we are very much pleased with the results. Sitemap files are generated several times a day for every language edition of wikipedia and the other wikimedia projects.

http://sitemap.wikimedia.org/sitemap/

Wow, Mathias, that's interesting news! Have you tracked it for changes compared to before the sitemap?

But you still have to send the sitemap to each search engine separately. That's not good. This should work automatically, like robots.txt mechanism.

2,5 time they teamed up, how about the NOODP Tag?

So far, I cannot provide you raw data, just experiences. A Wikipedian wrote the article about Sarah Kane in de.wikipedia. The article was well-linked within wikipedia and several blogs were pointing to the article itself. It took google about 2 month to finally index that page. This is now down to a week.

http://de.wikipedia.org/w/index.php?title=Spezial:Newpages&namespace=0&limit=500&offset=0

is a list of recently created articles (replace de. with your isocode and Spezial: with Special:).

http://de.wikipedia.org/wiki/Multiplikatorenmodell was newly created about 24 hours ago and so far, it is not indexed.
http://www.google.de/search?num=100&hl=de&safe=off&q=site%3Ade.wikipedia.org+%E2%80%8EMultiplikatorenmodell+&btnG=Suche&meta=

http://de.wikipedia.org/wiki/Anstellwinkelschwingung
50 hours ago: not yet indexed
http://www.google.de/search?num=100&hl=de&safe=off&q=site%3Ade.wikipedia.org+Anstellwinkelschwingung+&btnG=Suche&meta=

http://de.wikipedia.org/wiki/Gambelmeise
75 hours ago: not yet indexed
http://www.google.de/search?num=100&hl=de&safe=off&q=site%3Ade.wikipedia.org+Gambelmeise+&btnG=Suche&meta=

‎Abwasserpilz
100 hours ago: not yet indexed
http://www.google.de/search?num=100&hl=de&safe=off&q=site%3Ade.wikipedia.org+%E2%80%8EAbwasserpilz&btnG=Suche&meta=

created: 01:41, 12. Nov. 2006: indexed
http://www.google.de/search?num=100&hl=de&safe=off&q=site%3Ade.wikipedia.org+%22F%C3%B6deralistische+Union+Europ%C3%A4ischer+Volksgruppen%22&btnG=Suche&meta=
created: 01:34, 12. Nov. 2006 : indexed
Lucius Cornelius Latinianus

(YMMV)

I think it's great news that Google can influence other search providers to follow the standards. Sitemaps are great.

A good day for webmasters. I wonder though if there are downsides to this. People in forums report that after using Google sitemaps they fell down in the search results due to being downgraded to the so called "supplemental index". I wonder if any of you experienced this as I am sometimes suspicious about SEOs writing such stories, you never know which shade their hat is ;-)

Tadeusz, could be an unrelated coincidence though. Just imagine if of 100 webmasters 10% fall into the supplemental results every month, and 50% webmasters are starting on Sitemaps every month... that would mean 5 new stories each month on how Google Sitemaps ruin your rankings even when they don't! Kinda like how someone from Mars watching Earth might conclude that a group of people taking an umbrella with them in the morning will trigger the clouds to rain...