Apple released several updates Tuesday, including updates for AirPort Utility, AirPort Client, iLife Support, and iPhoto. The two AirPort updates include "general fixes," roaming issues, and support for dual-band environments. They follow the release of a new AirPort Extreme base station and Time Capsule with dual-band support. The iLife Support and iPhoto updates include various and sundry (and unspecified) fixes.

From the descriptions in Software Update:

• AirPort Utility Software Update 2009-0001 (version 5.4.1): a 19.5MB download
  This update includes general fixes and compatibility updates for the following applications: AirPort Utility and AirPort Base Station Agent, including AirPort Disk Utility for Tiger.
• iLife Support (version 9.0.1): a 52.3MB download
  This update improves overall stability and addresses a number of other minor issues. It is recommended for all users of Aperture, iLife ’09, and iWork ’09.
• AirPort Client Update 2009-001 (version 1.0): a 1.8MB download
  This update is recommended for all Intel-based Macintosh computers running Mac OS X 10.5.6. It addresses issues with roaming and network selection in dual-band environments.
• iPhoto Update (version 8.0.1): a 13.6MB download
  This update improves overall stability and addresses minor issues in a number of areas, including internet connectivity, keyword import, and slideshow export.

You can find all four updates in Software Update.