Per a MacSurfer.com link, MacUser.co.uk posted a report on the new iBook. From their sources, it appears G3's seem to be throttled at 700mhz presently:
However, Apple has been unable to procure G3 chips running at faster than 700MHz despite the announcement of a 1GHz version from IBM last year, this product is yet to ship. Apple has also so far rejected calls to move the iBook which is its last remaining G3-based product to the G4 processor. Sources have indicated that this is in order to maintain a distinction between its consumer and professional portable lines...
They also mention that the iBook may need a redesign to incorporate a G4... but appears to be speculation on their part.
