In the “following up old threads” department, I went back to Apple’s site to check if there was any news regarding the “insufficient bandwidth” issues that have kept us from using video chat features since I upgraded to Tiger. And sure enough, Support Article 301641 has been updated. Where it used to discuss QoS related issues with ISPs, it now suggests upgrading to 10.4.2 (which contains iChat AV 3.0.1) to fix the problem.
I’m looking forward to trying this out tonight. It will be nice to be able to chat with my inlaws again. The update apparently doesn’t fix all the issues, though this thread on the Apple forums is a pretty good rundown of troubleshooting methods to address remaining problems.