The key here is that linux doesn't assume one user. You get to answer, from
first principles, whether a particular USB device belongs to user x or to
root, etc. The mac has a stronger assumption that your mac belongs to you
(which is why the default hostname is "Dave Turner's Mac", etc) and what
you plug in does too.

I like the way KDE handles/handled USB sticks: The version of KDE I'm
running asks me about USB sticks the first time and remembers each stick
forever, so if I plug in my keyring stick now the linux box will automount
it. That would be a fine way to handle phones too.

Arnt