From virtualization.info:
Oracle just released its first updated for VirtualBox after the acquisition of Sun.
The list of bugs corrected in version 3.1.4 is long but there are no new features .
An interesting thing is that the company decided to change the default behavior of the engine: now VirtualBox tries to leverage hardware virtualization acceleration by default, and this includes both VPDI and nested paging, provided by Intel VT-x and AMD-V RVI enhancements.