Looks like there'll be new extended versions of I and II coming out just before III:

] Running times for the extended editions are 208 minutes
] for "Fellowship of the Ring" and 214 minutes for "The Two
] Towers."

] Starting the week of Dec. 5, the extended DVD cut of
] "Fellowship of the Ring" will be released in some 100 or
] so theaters in the U.S. and in 20 theaters in Canada.
]
] Then, the week of Dec. 12, sequel "Two Towers" will
] unspool, just a month after having preemed on DVD,
] leading up to a worldwide Dec. 16 daylong marathon,
] during which all three films will be shown back-to-back.
] Exhib guidelines call for a 3 p.m. showing of
] "Fellowship" followed by a 7 p.m. screening of "Two
] Towers" and then an 11 p.m. screening of "Return of the
] King," which will carry over into Dec. 17 -- the day of
] its global release.

Three and a half hours of I, followed by three and a half hours of II, followed by "Return of the King". Popcorn-overdose, dude, I'm there! :)