My wireless card firmware has gone from 1.3.2 to 1.3.4 but I haven't noticed any difference to performance at all. As soon as I take my MacBook more than about 15 feet from the airport I stop getting its signal, (I used to be able to take it 100 feet from the airport and get a good signal.)
Meanwhile my iBook with 10.4 working with the same airport express can get a signal 100'+ away from it.
If this is "the fix" for Macbook airport woes I'd say we are stuffed. I've just ordered a USB adaptor so I can at least use it when I travel at wifi hotspots.