I don't think this statement is correct. snapshot.debian.net seems to have all dates up to and including 2009/03/28, that date is after the release of lenny rc1 afaict.3) The relevant versions are now no longer available anywhere [2]: they are no longer in the archive and we don't have a snapshot.d.n for that period.
Note: the search function on snapshot.debian.net stopped updating long before the actual archiving stopped, and also 2009 doesn't appear in the index of archives (but the early 2009 stuff is accessible through manually typing urls) don't display properly.