I want to give a demo to people remotely. I want them to be able to use any VNC client to view my current Mac desktop. Can I use the built-in screen sharing features to do that? I'm using Mountain Lion (10.8.2). I don't want to set up a special "guest" account. I don't want to share my MacOS password with them. Everything I try under "Screen Sharing" gives the VNC user a Mac login screen, and doesn't connect to the existing desktop. When I enable the "remote management feature" it connects directly to the existing session with full control. I don't want all the viewers of my demo to have full control of the desktop, although that may be an acceptable work-around.
Probably too late to be useful, but if you look under "Options" for remote management, you can set whether viewers connecting with Screen Sharing can "Observe", or "Control".