The major impact these drivers will have is in making Amithlon usage on laptops a much more attractive proposition by enabling network and sound support for them. Up to now, this would have been a major drawback.
These drivers also seem to work better than the officially supported ones, so they may well add reliability to users who already had network and sound support on their desktop systems.
With regard to a Pegasos equivalent, I believe Bernie will release this under the GPL when he is ready to do so. However, it's just a hobby project and unlikely to have the same impact that the x86 version did, for obvious reasons.