A new release of jQuery 1.2.6 comes with lots of bugfixes, major improvements and many new features. Key performance improvements include 103% Faster Event Handling, 13% faster CSS selectors, 21% faster .offset() and 25% faster .css().

New features and major changes in jQuery 1.2.6 : </p>

• The Dimension plugin by Brandon Aaron is now part of the jQuery core.
• .attr() method has been completely overhauled
• .toggle() can now accept more functions
• unbind bound .toggle() and .one() functions
• .index() supports jQuery collections
• jQuery.makeArray can convert ANYTHING to an array.
• beforeSend can cancel Ajax calls
• Exposed Speeds

More info: jQuery.com