VirtualBox v4.3 Beta 1 is released. VirtualBox is a general-purpose full virtualizer for x86/x64 hardware. Targeted at server, desktop and embedded use, it is now the only professional-quality virtualization solution that is also Open Source Software.

VirtualBox v4.3 Beta 1 Changelog:
VMM: major rewrite of the VT-x code including many bug fixes and performance improvements (for example bug #9659)
GUI: keyboard shortcuts management (input page of global preferences extended with possibility to edit general keyboard shortcuts for VirtualBox Manager and Virtual Machine)
GUI: extended messaging mechanism (new non-modal popup overlays used to show non-critical warnings and provide user with additional information)
GUI: video capturing support (bug #4766)
GUI: host touch devices support (GUI passes host touch-events to guest)
Emulated USB touch devices
VRDP: support for IPv6
NAT: experimental virtual router mode: several VMs are attached to the same internal network and share one NAT service (see the manual for more information)
In addition, the following items were fixed and/or added:
VMM: properly handle NMIs on Linux hosts with X2APIC enabled
GUI: update check uses https
GUI: lot of internal stuff rewritten (cleanup and bug-fixes)
Settings: global and per-VM default frontend configuration, useful to select the use of alternative VM frontends
Settings: limit depth of snapshot tree to 250 levels, as more will lead to decreased performance and may trigger crashes
Main: new event queue implementation which does not use the host's native event queue for processing VirtualBox events anymore
Main: use the XDG standard configuration folder instead of .VirtualBox on systems where it is appropriate (bug #5099)
VBoxManage: list more information about hard disk/DVD/floppy media, and support the --long option to show really all available details
VBoxManage: added support for optional command line parameters for the automatic Guest Additions update
VBoxManage: added support for listing active guest sessions, guest processes and/or guest files via guestcontrol list
VBoxManage: added support for closing active guest sessions via guestcontrol session close --session-id | --session-name |--all
VBoxManage: added support for terminating active guest processes via guestcontrol process kill|close|terminate --session-id | --session-name ... or guestcontrol [p[s]]kill --session-id | --session-name ...
VBoxManage: added support for watching guest sessions via guestcontrol watch
3D support: several fixes
3D support: several fixes for Mac OS X hosts
OVF: several fixes
Keyboard: fix for reporting key sequences like Ctrl+Alt+Del for the USB keyboard emulation
Shared Clipboard/X11: support for BMP-format images, contributed by François Revol
Windows hosts: don't cause massive DPC latency (bug #6242)
Windows hosts: consider symlinks when retrieving volume information (bug #11962)
Windows Additions: fixed misbehavior with guest display power management (WDDM driver only; bug #11170)
Windows guests: ability to track guest user idle times through the newly introduced event IGuestUserStateChangedEvent

Download: VirtualBox v4.3 Beta 1
Source: Here