VirtualBox is a general-purpose full virtualizer for x86 hardware, targeted at server, desktop and embedded use. The following major new features were added: support for cloning of VMs (bug #5853) Support for PCI passthrough for Linux hosts, see the manual for more information. Support for Windows guests: Experimental WDDM graphics driver, supporting Windows Aero. New Crossbow based bridged networking driver for Solaris 11 build 159 and above. New Networking Mode UDP Tunnel allows to interconnect VMs running on different hosts easily and transparently.
Source: https://thehackernews.com/2011/07/virtualbox-41-final-for-linux-released.html