Don't install this update if your primary network connectivity is wireless and if you are using real time audio applications! This causes your audio in/out to stutter, at least when using low latency settings (hence real time). The issue has supposedly been reported to Apple, also by various developers/vendors so I really hope they sort this our ASAP.

If you've installed the update (like me) you'll have to turn Aiport off to make the audio stutter/drop outs go away. Not sure if it's possible to revert back to an earlier Aiport driver version. I'm running 10.4.11 BTW, not sure if the issue also concerns 10.5.x users.