Oracle recently released a major upgrade to its desktop virtualization VirtualBox tool. Virtualbox 4.3 includes some very cool features like Multitouch host support, Video recording and IPv6 networking. This newest release from Oracle i.e. Virtualbox 4.3.2 is a maintenance release and includes bug fixes, especially a much highlighted one, fixing the issue regarding Virtualbox not running on Mac OS Mavericks.
You can download this version from here. Here is the changelog listing the bug fixes.