Eric Gustafson writes:

> the above is true, with one addition...if the year is 3600, it is NOT a
>  leap year.  I don't know if the rule is "divisible by 3600, or just
>  3600"...does anyone know?

From the ultimate source on all things calendaric, the answer is:

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Leap Year Myths and Facts

Please do not try to discuss these myths, or try to prove that they are not
myths, on the Year 2000 mailing list or in other on-line discussion forums.
We have all had our fill of leap year discussions. There are much more
critical issues to be resolved, and time is running out.

Myth: If the year is evenly divisible by 3200/3600/4000 (pick one) it is not
a leap year.

Fact: There is no such rule. The two rules given above are the complete rules
for determining whether a year is a leap year in the Gregorian calendar. The
popularity of this myth seems to derive from the fact that the average length
of the year in the Gregorian calendar is approximately 26 seconds longer than
the tropical or solar year. This difference amounts to one day in a little
over 3300 years, or about three days in 10,000 years. Some experts have
proposed rules similar to the mythical rule to correct for this difference.
But no government, standards organization, or other authoritative body has
adopted such a rule.

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(ripped from the pages of:
http://www.magnet.ch/serendipity/hermetic/y2k/faq/y2kfaq04.htm)

Wirt Atmar