In addition to the specific install made for Snow Leopard fixing my
first problem (preferences wouldn't render, etc..), I ended up running
in to another problem post setup where the application would no longer
launch.
I removed the contents of the plugin directory, and that cleared the
problem. My specific problem is exclusive to a single plugin, the
airport module.
So, in case you're installing plugins and biting your nails without
knowing which caused your problem, this may be a good candidate. I
have yet to experience any problems with other modules.