Of course this depends on whether or not there is actually root access to be gotten. There has been no information about the version of OSX (Liger? Tigon?) that will be included on the iPhone. There may not be a root to be gotten. The root account is disabled on default installs of OSX. There is no reason to asume that it will be enabled on iPhone.
That said, I give it less than a month before someone figures out how to have complete control of the thing.