Not sure what the issue is, I have Lion Server running fine on ESXi 5 (just not had time to run it on W8), which is the same code as Workstation 8. There is no Server only install in Lion, you install the client and the use the App Store to add Server. The only thing, I am still on 10.7.1, only because of the issues with 10.7.2, and I have not had the time to apply the fixes to make 10.7.2 work in VMware W8 or E5. I will try going straight to 10.7.3 and see if that solves the .2 issues, I had developer notification today or yesterday for the .3 seed.
[UPDATE] With the release of Workstation 8.0.1, I will see if this resolves the .2 issues.
I finally could not get the server going with VMware Workstation under Windows Server 2008 R2 so I decided to go with vSphere 5 and I have to say it runs very well. The server upgrade kept hanging on configuring services and although I could get it to reboot, I could not get the Server app to work - I had to connect from a separate computer. I actually have both OS running concurrently and have setup the server to auto shutdown and so far this has worked perfectly. I am still on 10.7.1 since Esxi has not been upgraded since August as far as I know. The only bad thing about this is that I had a cheap software raid card in my server that is useless now. Additionally, my backup esata array drive will not work with esxi (I will have to connect it to a NAS).
Just writing this as a follow-up. BTW I had to install SL Server and upgrade from there to get it to work in my hardware: ASUS p7H55 m pro/Xeon x3450 16GB Kingston DDR3 1333MHZ/OCZ 200GB SSD with 7TB HD storage.