The key features, according to Oracle in their forum release announcement, for VirtualBox 4.1 Beta 1 include:
- Support for cloning of virtual machines.
- Enhanced wizard for creating new virtual disks.
- A new wizard for copying virtual disks.
- The VMM has a raised system memory limit for 64-bits to 1TB.
- Windows guests can now use an experimental WDDM graphics driver. WDDM is the Windows Display Driver Model and is a new graphics driver architecture that was introduced in Windows Vista and has been continued in Windows 7 as a replacement to the Windows XP driver model. Microsoft's claim is that WDDM drivers can be faster and deliver more features.
- Modules and features for VirtualBox Guest Additions now are represented as facilities to have a common interface for front-ends.
- UDP Tunnel as a new networking mode to interconnect virtual machines running on different hosts easily and transparently.
There's also 23 listed bug-fixes for VirtualBox 4.1 Beta 1, including SMP timer fixes, GUI proxy settings, reduced NAT memory footprint, support for TLS connections with VRDP, and various other items. Sadly, it doesn't look like Oracle engineers did anything to improve the OpenGL guest acceleration support for Linux operating systems. Oracle may be in support of Microsoft's WDDM driver architecture, but they still aren't convinced about Gallium3D for VirtualBox on Linux.
See more or download from the mailing list announcement for Oracle VirtualBox 4.1 Beta 1.