"Hey Siri" support and possibly wireless charging case alongside AirPower charging mat.
AirPods and AirPower: Everything We Know
PowerBook Edu Discounts
"And for a limited time, you can save up to $380* off the retail price of a PowerBook G4 -- this includes up to an additional $150 savings on top of the regular Apple Store for Education Individuals discount. Act now, this special back-to-school offer expires September 25, 2002."
Several readers have suggested that this may hint towards upcoming revisions, however, there is no further indication that the PowerBook G4 will be updated this soon. In fact, the only evidence is to the contrary... with PowerBook rumors for January.