SharePoint 2007 has a problem finding people by birthday.
If you view a person's profile (their "My Site") and click on their birthday, you're taken to a People Search for a term like this:
However, that never returns any results. If you amend the search term to:
Birthday:"22 March 2000"
... then the person appears in the search results (as well as anyone else with March 22 as a birthday).
It seems that the "Date No Year" data type is stored internally as a traditional date with a year of 2000, and the crawler isn't smart enough to ignore that, so birthday searches always fail.
Is this fixed in SharePoint 2010?