Update to version 3.8.

Changes:

Introduces a new, modern admin design
* A fresh, uncluttered design
* Clean typography with Open Sans
* Superior contrast and large, comfortable type
* Responsive interfaces throughout
* Refined, theme management
* Smoother, click-to-add widget management

New Default Theme - Twenty Fourteen
* Easily create a responsive magazine website with a sleek, modern design.
* Feature your favorite homepage content in either a grid or a slider.
* Use the three widget areas to customize your website, and change your
  content's layout with a full-width page template and a contributor page to show
  off your authors.

For Developers
* External Libraries have been updated.
* Better RTL support

More info on http://codex.wordpress.org/Version_3.8

(morr)