Yesterday, WordPress 2.7 Release Candidate 1 (RC 1) has just been released by WordPress.org. This version comes with new interface and new icon set. Bellow is the quote from WordPress.org Blog:
With the release of RC1, we’re in the final leg of development before the release of 2.7. 280 commits since beta 3 have polished the new admin UI (including new menu icons created by the winners of our icon design contest) and fixed all known blocker bugs.
Screenshot of WordPress 2.7 RC1 with new icon set. It's so cool!
I recommend you to update to this version now. But before updating, don't forget to backup your blog database first!