This release fixes security vulnerabilities. Sites are urged to upgrade immediately after reading the security announcement:

    * SA-2008-060 - Drupal core - Multiple vulnerabilities

In addition to this security vulnerability, the following bugs have been fixed since the 6.4 release:

* - Patch 246143 by bjaspan, Damien Tournoud: make sure updates are run in numeric order, not in definition order.
* - Patch 221230 by Heine: convert requirement error on update to requirement warning.
* - Patch 252430 by quicksketch: allow base theme prefix in preprocessor function names to correct expected behavior.
* - Patch 245322 by mfb: fixed breadcrumb behavior.
* - Patch 287949 by Freso, Damien Tournoud: keep language icons in consistent order across nodes.
* - Patch 265899 by mfb: uri_brief mail token did not support https URLs.
* - Patch 272952 by NancyDru and chx: fixed documentation issue.
* - Patch 170310 by mfb, JohnAlbin: avoid SSL cookie getting over-written by non-SSL cookie.
* - Patch 243063 by GoofyX: fixed typo in context-sensitve help.
* - Patch 295152 by dww, Damien Tournoud, et al: fixed version comparison.
* - Patch 278759 by douggreen, fletchgqc: improved code comment.
* - Patch 276018 by mfb: extend the lifetime of temporary files.
* - Patch 228576 by sun: too ambiguous stylesheet in dblog.css when form_altering the watchdog table.
* - Patch 285309 by pwolanin: menu_name in hook_menu is ignored on updates.
* - Patch 261859 by rse, Damien Tournoud: make the trigger module work on PostgreSQL.
* - Patch 305436 by Damien Tournoud, lelutin: fixed unclosed <li> tag in the context-sensitive help.

Any many more.  See http://drupal.org/node/318701 for all the details

(adrianp)