After installing Mac OS 10.5 Leopard numerous MacBook and MacBook Pro users' keyboards and trackpads would spontaneously stop responding to user input. Some would awake after a minute or two, but most users were forced to ungracefully reboot their machine to regain control of their keyboard.
Yesterday Apple released MacBook, MacBook Pro Software Update 1.1 (979kb) which is available via Software update which addresses the bug:
This update addresses a responsiveness issue on MacBook and MacBook Pro notebook computers. Some MacBook and MacBook Pro systems may occasionally experience a temporary suspension of keyboard input which can last a minute or longer. The Mac OS X 10.5.1 update is required before installing the MacBook, MacBook Pro Software Update 1.1.