It really pays off not to take updates (that require a restart) right away! This evening Apple sent out Time Machine and Airport Update v1.0 which according to the sparse release notes:
...includes compatibility improvements for using Time Machine with Time Capsule, as well as Airport driver fixes.
Could this update be the fix for the annoying Airport dropout issues introduced for some (including me) with 10.5.2. I guess this update could just as easily make those issues worse. At this point I have 90-something MB of software updates waiting for me to install this Friday after I back up. Enjoy, Alex.