The DateTime::Language modules are no longer being developed or distributed as part of the DateTime.pm distribution.
Because of this, all "language" parameters should now be replaced by "locale" parameter. The "language" parameter is deprecated and will be removed in a future release.
Also note that locales should be specified via ISO codes, not names like "English". The old DateTime::Language names will continue to work indefinitely, but they load DateTime::Locale objects instead.
Similarly, the "language" and "DefaultLanguage" methods are now deprecated in favor of "locale" and "DefaultLocale".
IMPROVEMENTS
DateTime::Duration now returns the object from mutator methods, in order to make method chaining possible. Suggested by Ben Bennett.
If the value for second given to new() is 60 or 61, then it must be a valid leap second.
DateTime now uses DateTime::Locale for localization, which allows for real language and territory based localization. The locale code is generated from the ICU project's data, and is much more complete than the DateTime::Language modules. However, we are losing (hopefully only temporarily) support for the various African languages contributed by Daniel Yacob. Support for those languages should return in a future release of DateTime::Locale.
Support for the '%c', '%x', and '%X' strftime format specifiers, which output localized date and time strings.
Added the time_zone_long_name method, primarily for the benefit of DateTime::Locale.
Added a note to the DateTime::Infinite docs warning that it may not work well on Win32.
BUG FIXES
DateTime::Duration was not consistent in how it handled mixed positive and negative constructor parameters. Reported by Ben Bennett.