Oracle announced this morning the release of their VirtualBox 4.3
cross-platform virtualization software.
Oracle VM VirtualBox 4.3 supports virtual multi-touch guests, new devices and platforms, Windows 8.1 compatibility, OS X 10.9 Mavericks support, a new virtual USB webcam, networking improvements, and a wide variety of other fixes.
More details on VirtualBox 4.3 can be found via the Oracle press release
or the VirtualBox.org announcement