updated 09:35 pm EDT, Thu October 30, 2008
MacBook Kensington locks
The late 2008 aluminum MacBooks and MacBook Pros are allegedly incompatible with Kensington locks. Apple lists the feature as a "Kensington lock slot," but owners have reported that the thickness of the aluminum prevents the standard locks from being used. A response from Kensington's technical support department was claimed to read "we are sorry to inform you that the security slot of your laptop 'late 2008' Aluminum MacBook is not compatible with Kensington locks."
The solution recommended by the lock manufacturer involved a K-Slot adapter, but that would require gluing a plastic piece to the case of the notebook. Gluing an object to a MacBook would not be attractive for most owners.
It is unclear if the issue only applies to certain lock manufacturers. Kensington lists the thickness tolerances for the lock slot depth as 2.5mm to 4mm. Companies could already be working on new locks to fit the design, but detailed information regarding the new lock slot is limited.
[Credit for tip goes to Michael]