VMWARE WORKSTATION 5.5
Back in November, VMware released version 5.5 of their Workstation virtual machine product. Overall it's not a big improvement over version 5.0, but might be just the right "next step up" for those still on Workstation 4.x.
For me, the biggest improvement in VMware Workstation 5.5 is the wireless networking support in GNU/Linux. With version 5.0, I was unable to bridge a wireless network connection to a virtual machine, which pretty much robbed the guest OSes of networking capabilities. Bridged wireless networking now works flawlessly in GNU/Linux.
VMware claims that there is better device autodetection, but ever since the first version of VMware I tested -- 4.0 -- I have not had any trouble with internally installed hardware being detected and used in a virtual machine.