nuevojefe - 7:41 am on Dec 10, 2007 (gmt 0)

Try doing a search for a few unique phrases from your page. Try without quotes then with. See what pops up. You can use copyscape too. Besides external copies you may find the content is being indexed in duplicate internally as well.

Although obvious, check the /robots.txt file to ensure no tampering or accidental exclusion. Same with htaccess or similar if not in apache.

Check your backlinks as well (linkdomain:domain.tld in yahoo). Might spot something out of place there.

Do a site:domain.tld search in google to see if any pages are indexed at all.