Apple today released AirPort Extreme Update 2007-003 which is recommended for all Intel-based Macintosh computers and includes compatibility updates for certain third-party access points configured to use WPA or WPA2 security.
• Mac OS X 10.4.8 or later
• Intel-based Macintosh
• AirPort Extreme Update 2007-002
AirPort Extreme Update 2007-003 is available via Software update and also as a standalone installer.
More info and download link (3MB) here.