AppleInsider provides a look at Leopard's updated iChat 4.0 application.
A couple of useful new features are detailed, including Document Sharing:
Any file that can be viewed with Quick Look can be "beamed" with document sharing. While the document is being shared, the sender sees it in a Quick Look panel view, while the viewer on the other end sees the document as a video chat.
and Screen Sharing:
There hasn't been a really simple and obvious way for users to set up a screen sharing session however. In the new iChat, it's effortless. Click the new screen sharing icon in iChat for any user that can support the feature, and it drops down two options: share my screen or request to share theirs. Once the user on the other end approves the connection, a VNC session is setup.
The appeal of Screen Sharing is that remote troubleshooting can be easily initiated without the requiring the end-user to go through a technical setup to enable screen sharing. Now, anyone who can iChat can share their screen if desired.
Apple also details the features of iChat and has published a list of 300 new features found in Leopard.
Apple announced today that Mac OS X Leopard will go on sale on October 26th, 2007 at retail Apple Stores and you may pre-order it starting today.