It doesn't affect only USB audio devices but also FireWire. Their solution is to quit the app before disconnecting the device. Seems pretty lame, I hope they fix that in a patch before releasing 10.3. We have a bunch of Macs which we want to switch to OS X this Summer but we'll be going with 10.2 because that's what we already own.
That reminds me, this year, we need to make sure our Mac orders are placed late enough to definitely get 10.3. included.