It happened recently today. From the Apple Product Security mailing list:

APPLE-SA-2006-09-21 AirPort Update 2006-001 and
Security Update 2006-005

The security fixes described below are available in AirPort Update
2006-001 and Security Update 2006-005. AirPort Update 2006-001
contains an additional non-security fix to address a reliability
issue that occurs on a limited number of MacBook Pro systems.

AirPort version 4.2:
www.apple.com/support/downloads/airport42formacosx1033.html

About the security content of AirPort Update 2006-001 and Security Update 2006-005:

docs.info.apple.com/article.html?artnum=304420