It would be a little faster. The first part of copy.copy looks like

  def copy(x):
    """Shallow copy operation on arbitrary Python objects.

    See the module's __doc__ string for more info.
    """

    cls = type(x)

    copier = _copy_dispatch.get(cls)
    if copier:
        return copier(x)

    # more after this point but it's not relevant for lists

So calling copy.copy on a list over using list() will check for the type, look up the type in a dictionary after which it will proceed as if you called list() yourself.

Mental memo. :)

I'm not sure either... A hand-written .clone() method would always beat the generic solution of course, but it seems like the tradeoff is that you spend less time coding, which is a win.