According to the Online Apple Store, the Airport Extreme Base Station's ship date has slipped to "mid-November". Such a delay would seem to indicate Apple is readying a revision is nearing. However, the extent of the revision is not currently known, as the update may simply be to pass relatively new European environmental regulations (RoHS) that has stopped the sale of the base station and the iSight in Europe since June 30th. The iSight is also facing a similar shipping delay, with a stated ship date of October for U.S. online apple store customers.
Note: Users hoping for an update that supports the upcoming IEEE 802.11n spec may not want to hold their breath, as the spec has faced repeated delays and currently is not expected to get final approval until 2008. While Apple's original Airport base station was "pre-802.11b" compliant and a firmware upgrade made the station compatible with the finalized spec, the current situation is different and the changing nature will likely render any "pre-802.11n" devices not compatible with the final specification (making an adoption by Apple unlikely at this time).
Update: Forum member treblah has pointed out that while IEEE certification of the spec is a ways off, the WiFi alliance will most likely certify to some degree the draft specification for pre-N products.
Also of note, in June the primary makers of 802.11n chip-sets claimed interoperability which was a large barrier towards certification.
