I couldn´t find any information on the documentation of VMware about this topic. Any advise on where to find information on this is very appreciated.
VMware workstation, fusion and player are desktop productions that run on top of other operating systems like windows, linux and mac os. VMware ESX, ESXi run on bare metal directly. Since VMware Infrastructure 3 is built upon ESX and ESXi 3.X, it is ok for you to run workstation on top of VI3. But it should be pointed out that workstation running on VI3 won't support hardware virtualization even if your physical cpu ships with hardware virtualization solution. However, latest ESXi and even workstation support so called "nested virtualization" in non-production environment. Actually, I have a virtual ESXi 5 server that runs within my fusion 5.