WordPress 2.5, the culmination of six months of work by the WordPress community, people just like you. The improvements in 2.5 are numerous, and almost entirely a result of your feedback: multi-file uploading, one-click plugin upgrades, built-in galleries, customizable dashboard, salted passwords and cookie encryption, media library, a WYSIWYG that doesn’t mess with your code, concurrent post editing protection, full-screen writing, and search that covers posts and pages.

A list of all the changes can be seen at Wordpress>/a>.