Screen sharing via iChat in the Leopard is indeed awesome and amazing. However, there’s a better way. Here are my issues with the default screensharing via iChat:

1. It’s modal—you can’t click on any other application or interact with your own desktop in any way while sharing someone else’s desktop
2. It’s fullscreen, but it’s not—it takes over the whole screen, but there’s a black border around it if the screen you are sharing is a lower resolution than your screen so you still can’t get to your own desktop behind it.
3. You can’t select which desktop you want to see if they screen sharer has multiple desktops. You get all of them. If you are sharing with someone who has dual 30” displays and you are trying to view it on a macbook pro screen, that’s a real pain.
4. You can’t share with more than one person. If I were doing default VNC (which is the underlying protocol for Leopard screen sharing), I could allow as many clients as I want to view my screen. With Leopard, it’s one only.
5. I can’t have a view-only client. With VNC (typically we use the Vines server and Chicken of the VNC client) I can connect my client as view-only so I don’t have to worry about mouse contention with whoever is driving the server. You can’t do that in Leopard.

Don’t get me wrong, it’s still very useful, but these things do add up to be quite annoying. I still don’t have a solution for #4 or #5 (any help would be appreciated, please comment), but I’m here to relieve you if you’ve struggled with #1-#3. It turns out that iChat is using another installed app as the backbone of the screen sharing experience. Venture into finder and take a look at

/System/Library/CoreServices/Screen Sharing.app

This is the actual Leopard screen sharing client and you can run it outside of the iChat context. You give it the address of the server you are trying to share (the sharee has to initiate this to get the screen of the sharer). You then have the option of logging in using a known user/password on the sharing computer, or you can request permission which prompts the sharing computer. In order to set this up, the sharing computer needs to have screen sharing needs to be turned on in System Preferences (under the Sharing panel), and if behind a firewall/router you need to have the VNC ports forwarded to the right internal IP (I forward ports 5900-5902).

It still does the same cool screen sharing, but you get these options as well. Under the view menu, you can select which display you want to share. You can easily use this to switch between displays, or go back to viewing them all if you really need to.

You can syncronize the clipboard contents of the shared machines. I can copy something to the clipboard on my end, then use the menu to sync the clipboards of the two machine. My pairing partner can then paste in the code/url/whatever that I just put on his clipboard.

The sharee (client) sees the shared content in a window that can be resized at will. It no longer consumes the whole screen, and you can have the focus on another application so you don’t accidentally contend for the mouse on the shared machine anytime it happens into the shared window. You can adjust the quality (adaptive vs. full) of the view as well which can help alleviate issues from sharing on a smaller or lower res monitor, or if you are trying to optimize network bandwidth.

If you want to have multiple clients, you still need to fall back to VNC/NX/etc, however using the actual screen sharing app instead of doing it through iChat has greatly enhanced remote pairing for me. Hope that helps.