The first thing youll notice about 2.7 is its new interface. From the top down, weve listened to your feedback and thought deeply about the design and the result is a WordPress thats just plain faster. Nearly every task you do on your blog will take fewer clicks and be faster in 2.7 than it did in a previous version. (Download it now, or read on for more.)
Next youll begin to notice the new features subtly sprinkled through the new interface: the new dashboard that you can arrange with drag and drop to put the things most important to you on top, QuickPress, comment threading, paging, and the ability to reply to comments from your dashboard, the ability to install any plugin directly from WordPress.org with a single click, and sticky posts.
Digging in further you might notice that every screen is customizable. Lets say you never care about author on your post listings just click Screen Options and uncheck it and its instantly gone from the page. The same for any module on the dashboard or write screen. If your screen is narrow and the menu is taking up too much horizontal room, click the arrow to minimize it to be icon-only, and then go to the write page and drag and drop everything from the right column into the main one, so your posting area is full-screen. (For example I like hiding everything except categories, tags, and publish. I put categories and tags on the right, and publish under the post box.)
Introduction video and rest of article here: http://wordpress.org/development/2008/12/coltrane/