For those of you that have read my prior post on Sun VirtualBox, you would already know that I think it is a viable alternative to VMware Server.  Although I do not feel it is strong enough to contend with VMware Workstation, I feel it definietely sits at the top of the free type-2 based hypervisor offerings.  The best thing about it is that it has a build for pretty much every operating system (including Mac).

In VirtualBox version 2.1.0 there have been a ton of enhancements and bug fixes.  You can view the entire list here.

Enhancements:

• Support for hardware virtualization (VT-x and AMD-V) on Mac OS X hosts
• Support for 64-bit guests on 32-bit host operating systems (newer 64-bit processor required)
• Added support for Intel Nehalem virtualization enhancements
• Experimental 3D acceleration via OpenGL
• Experimental LsiLogic and BusLogic SCSI controllers
• Full VMDK/VHD support including snapshots (use your VMDKs complete with snapshots)
• New NAT engine with signi?cantly better performance, reliability and ICMP echo (ping) support
• New Host Interface Networking implementations for Windows and Linux hosts with easier setup