Finaly Blender 2.59 released, This is mostly a bug fix release with 140 fixes since 2.58a. Additions include improved keymap editing, 3D mouse support, some new addons and Node UI improvements. What's cool stuff inside ?, find in here
3D Mouse support "NDOF"
Blender is now built with support for 3D Connexion devices, for more natural control during view navigation and fly mode.

Custom Keymaps
User edited keymaps now no longer override the builtin keymaps entirely, but rather save only the difference and reapply those changes. This means they can stay better in sync when the builtin keymaps change.

Ivy Generator (Addon)
This tools adds the ability to "grow" curves over an existing mesh with the option of adding leaves and adjusting many parameters for the final result.
Grease Scatter (Addon)
Grease scatter was used for sintel to place objects around the ally, using grease pencil lines as a guide as to where to scatter objects

And Many More
Find out what coll stuff else, visit Blender 2.59 Complate changelog, here.

Install / Upgrade Blender 2.59 via PPA
There is a best way for ubuntu user to install or upgrade Blender 2.59 on ubuntu 11.04, that is install trough PPA repository. As it wirite previously in here, follow this step to install or upgrade Blender 2.59 via PPA.
  • sudo add-apt-repository ppa:cheleb/blender-svn
  • sudo apt-get update
  • sudo apt-get install blender
Check this link to Blender 2.59 release log.