Note:You may not have received an update notification if you are running 4.0.x
Download your copy: http://www.virtualbox.org/wiki/Downloads [4]
Change log for this major release: http://www.virtualbox.org/wiki/Changelog [5]
Links:
[1] http://pulse.veltsos.com/category/it/open-source-foss
[2] http://pulse.veltsos.com/category/it/virtualization
[3] http://linux.philosweb.com/drupal/system/files/image_2_146.png
[4] http://www.virtualbox.org/wiki/Downloads
[5] http://www.virtualbox.org/wiki/Changelog