According to Jason D. O'Grady (PowerPage, posted on ZNet blog), Apple's next generation iBook will not have a FireWire port but only USB2 ports. The site also claims that the next Powerbooks will only have a FireWire 800 port.

FireWire is a technology Apple has created and promoted for years. All of its products since the early G3s currently have a FireWire port, that also includes peripherials like the iPod or the iSight. Since the release of the iPod shuffle, every new iPod released has seen its support for the FireWire technology dropped in favor of Intel's USB2 which isn't known to be better.

We may speculate that this move is related to Apple's commitment to Intel technologies, since the company announced earlier this year it was switching to Intel processors for its Macintosh products.