A root hack has been found for the ICS Leaked on D4, see this thread:
Droid4 ICS 206 Leak root hack, FINALLY.
I wrote one from scratch. You can get it here: Index of /
ics4.0root.gz and ics4.0root.zip are the newer script.
ICSRoot.gz and ICSRoot.zip are the older version.
It doesn't copy files to /sdcard. The first one I wrote copies the files and roots it directly from adb. The second one pushes a script to the phone and runs that to gain root. It gives me much more control over cleaning up if it fails since this hack requires specific things to be in specific places in specific conditions before the hack will work. If it fails during the hack the original script will make a mess of things but still recover. The second script will clean up any messes and make sure there aren't any files left hanging around or in the wrong place/state.