We know that Leopard supports screen sharing and that it's built on top of VNC. It turns out that you can do a Command-K in the finder, connect to server, and use a url like this: vnc://hostname to connect. If it's not running on the default VNC port of 5900 you can add the port in the usual way as shown in the picture.
As dreena is a a linux box, I get a warning dialog box as shown. The client seems very snappy and works nicely.
When I connect to an old Panther MacOS X Server it works just fine and obviously doesn't give the warning about keystroke encryption. Digg this.
I've noticed that the built-in VNC doesn't interoperate too well with the RealVNC server for windows. In this case Chicken Of the VNC seems to start up the session much faster for some reason.