ssh into the remote Mac and kill the screensharingd
daemon.
$ ps ax | grep screen
1234 ?? Ss 0:00.02 /System/Library/CoreServices/RemoteManagement/screensharingd.bundle/Contents/MacOS/screensharingd
$ sudo kill 1234
It works for me. I have Mac OS X Lion on both local and remote computers.
There is not a way to do this yet in FaceTime. Here's the link to a forum where they discuss how "neat" it would be to have this feature. The discussion is a month old, so fairly recent.
As for Screen sharing, if you're on the same network (either routed, through a VPN, SSH tunnel, or direct connection) then you just select the device in Finder, and choose screen sharing (button in the upper right hand corner) in the window that opens:
The computer that is sharing its screen must have Screen sharing turned on (check marked) in System Settings > Sharing:
Note mine is NOT check marked, so this computer would NOT share its screen using screen sharing.
If you want to Screen share and you are NOT in the same Network, use Messages:
Note Screen Sharing (under the video drop down)is enabled (has a check mark next to it).
Best Answer
Screen sharing on Skype is one-way only. Only one person in the call can share their screen with the other callers at one time. With the free accounts the sharing is limited to one-to-one. With the premium accounts you can do a one-to-many broadcast and share your screen out to multiple people at the same time.
This does make some sense, two-way sharing has to overcome a huge problem of mirror-in-mirror replication. The same sort of effect you get when you place two mirrors, facing each other, and look into them. There's an infinitely repeating, but gradually reducing, view of the other mirror, in the other mirror, in the other mirror, in the other mirror...
A similar thing would occur if you were to do a 2-way share.
If you use VNC for screen sharing you can actually force the two-way share to happen and see the effect for yourself.