New 1.1 revision of the Draft 802.11n standard
Although Apple is on the verge of migrating their whole range to 802.11n (except for the current-gen Mac mini), people need to remember that it is NOT an existing standard, only a draft. But a big step has been done when a new 1.1 draft was finalized and unanimously ratified by all the members. If the standard is not yet finalized, there shouldn't be any more changes on the hardware side, only modifications that could be implemented through software and firmware updates.