well i would imagine that if every major phone nowerdays seems to get rooted and custom roms added on release date. it will be more than possible if someone who knew what they were doing had a crack at it. i bought my note on release day, first thing i done was took it out the box hooked it up to the pc and rooted it put a custom rom on it then within a short while ics had been released way before samsungs official version. acording to the website i used they figured it out 3 days before the notes official release.
personally i have no idea how its all done i just follow the tutorials but it appears those cooking up the roms are finding it to be a peice of pi$$.