Automattic developers released the first beta of their next update last week.

WordPress 3.5 Beta 1 is available for download though is not recommended for use on public blogs.

Major changes in this edition:

Appearance: A simplified welcome screen. A new color picker. And the all-HiDPI (retina) dashboard.
Accessibility: Keyboard navigation and screen reader support have both been improved.
Plugins: You can browse and install plugins you’ve marked as favorites on WordPress.org, directly from your dashboard.
Mobile: It’ll be easier to link up your WordPress install with our mobile apps, as XML-RPC is now enabled by default.
Links: We’ve hidden the Link Manager for new installs.

This update also has a couple of goodies for third party developers.