Sorry to be coming to the game so late here. Disclaimer/credentials: I've worked in VMware's virtual machine monitor group since 2000.
AFAIK, virtualizing 64 bit guests does still require Intel VT or AMD Pacifica support on the CPU regardless on all products that support 64 bit guests.
You're close. AMD Opterons rev-D and higher can support 64-bit virtual machines without any specific virtualization hardware. They provide 64-bit segment limit checking, which enables our binary translator to work in a way similar to our pre-VT and -Pacifica products. See, e.g., http://communities.vmware.com/message/289914
Even if Pacifica technology is present, we don't default to using it for performance reasons unless "RVI", nee NPT, is also present. These came along with AMD's Barcelona chips in '07. Intel's response, EPT, is in Nehalem.