joda-time is a date-time library written in Java. It has advantages over Java's built in time utilities in terms of power and ease of use. It has some functionality that Python's own datetime library does not. Here is a sampling from within jython:
[OpenJDK Client VM (Sun Microsystems Inc.)] on java1.7.0-internal
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>>> import sys
>>> # make sure the jar is in the CLASSPATH
>>> from org.joda import time as joda
>>> rightnow = joda.DateTime()
>>> # I'm actually in New Mexico - close enough
>>> # days are one indexed along with months
>>> # a date from the past
>>> declofindependence = joda.DateTime(1776, 7, 4, 0, 0, 0, 0)
The Period object allows you to count down to dates in the future of count from dates in the past in terms of years, months, and days:
>>> americasage = joda.Period(declofindependence, rightnow)
joda-time can handle dates far into the future as well as those in the far distant past:
>>> farfuture = joda.DateTime(10000, 1, 1, 1, 0, 0, 0)
Like most things Java, joda-time can be a bit more verbose than its Python equivalent. Still, the ability to get dates beyond 9999 and some of the functionality may make it well worth the trouble.