The old PunkBuster files are not Intel-native libraries, so they will *deifnitely* not work.
The issue with the "No Packet Flow" is that the servers you are joining do not know about the new Mac Punkbuster libraries for this update, and the new version of CoD won't work with the old ones. It's a slight Catch-22, but it'll be fixed when the retail patch is released.
I'm going to go ahead and ask Tony at EvenBalance to push out the new Mac Punkbuster libraries so that all the PC servers can start to get updated. Once this happens, Mac users running the non-Universal Binary Call of Duty will be unable to play once they join, but that should be a problem only for the next week or so.