The Screen Sharing feature of iChat in Leopard is one of the most useful features. The Screen Sharing is based on Apple’s Remote Desktop package. Apple’s Remote Desktop Application can be used to maintain multiple computer but you have to pay $500 to buy the software. Luckily Apple left at least some of that functionality in the more-limited screen sharing application, which is disabled by default in Leopard. Macworld has posted complete instruction to activate these functionalities on your Mac. You should definitely check out complete details at MacWorld’s website.