It's easy, in theory, to get vnc to launch with a gnome desktop. However, in practice, there are a couple of problems.
The basics of getting gnome to work are to include a call to gnome-session in .vnc/xstartup
$ more .vnc/xstartup
This should work, except when a single user is trying to run multiple gnome sessions on the same machine. The symptom of this problem is an error in the log file saying that a session manager is already running. This can be solved by starting the vnc session on a different machine.
The next problem is there's no text displayed - the icons appear, but no captions. Inspecting the log files shows plenty of warning messages about invalid subfonts. The simplest way of dealing with this issue is to use a Solaris 10 system to host the vnc session