Ah, the joys of the web: A Lord of the Rings fansite posted a trailer for Return of the King last week, then quickly took it down at the request of New Line. I did a little looking around on various related message board sites (found via Gogle) and found a copy of the trailer that several people grabbed and archived elsewhere.
Comments on the trailer? A bit of a downer in mood, of course, but leaves you wanting more. Fell beasts, the Siege of Minas Tirith, big armies, a scheming Gollum, fun in Mordor, a reforged Anduril, and more in just over a minute and a half.