I have heard different things from different sources about weather VMWare Fusion runs correctly under 10.6. Turns out that Fusion runs in 32bit mode and unless you are running Fusion on a Snow Leopard server, you should be OK.

VMware Fusion 2.0.5 offers experimental support for the default install of Snow Leopard, which runs both 32-bit applications and the new faster 64-bit applications on the default 32-bit kernel.

I have heard reports that Fusion does run as described by VMWare in 32bit mode.