Leopard's new and improved iChat boasts two features that are sure to enhance both workplace productivity and friends and family tech support: screen sharing and document sharing. In a nutshell, iChat now makes it dead simple to review documents with one or multiple chat partners in what it calls iChat theatre (pictured) or share screens—either your screen or the screen of the person you're chatting with—VNC-style. That means that not only can you see what's going on with the other person's screen; you can also control it. To use either feature, all parties need to be running Leopard. For screen share, you can right-click the contact and choose either "Ask to Share Contact's Screen..." or "Share My Screen with Contact..." and iChat will send out the invite. Likewise, if your contact sends a request to you, you'll get an alert asking you to accept. Imagine next time your parents call you up with a completely inexplicable computer problem or question ("It keeps going blank when I click on the blue thing?"). Rather than banging your head against the wall trying to understand what they're talking about, just fire up iChat (assuming you both are running Leopard) and see exactly what the blue thing is.
When you're in control of another computer, you'll view it fullscreen like it's your own desktop, while your desktop appears in a small window in the corner (see screenshot). You can switch back and forth between desktop controls by simply clicking that window.
Then there's document sharing. To share a file, go to the menu bar and hit File -> Share a File with iChat Theater. Once you choose the file to share, you'll see an iChat window like the one above with your document as the focus and your contact floating next to it. If you're sharing the file, you'll also get a quick preview look at the file from which you control where you're viewing the document. As far as I could tell, the person sharing the file is always in charge of what the viewers are seeing from the document. iChat Theater seems like an excellent way to remotely collaborate on a document that needs reviewed or needs changes approved.
Lastly, you can also share iPhoto albums via iChat Theater, making it an excellent way to pore through pictures of the kids with their grandparents.