Convert Apple binary plists to xml plists and back again

Apple binary plists can be converted to human readable xml thus:

plutil -convert xml1 binplist.plist

And, should you have the need, can be converted back again:

plutil -convert binary1 binplist.plist

It's worth noting that this is an in-place conversion that will overwrite the original file and so you should make a copy if whatever part of the OS you're messing around with first.