See my note in the Ana Lucia post about these Fan based Rumors.
"Who could have possibly been on the airplane I was on heading for Hawaii yesterday? I would have never noticed except the flight attendants made a big deal out of it. We were both up in first class but he was in the very fist row with all the legroom and he had his privacy. This he I speak of is of course Nestor Carbonell, a.k.a. Richard Alpert. As he departed the airplane with his wife/girlfriend, I asked him if he was filming Lost again. He and his wife smiled and they said he couldn't say anything. He said that he wasn't in Hawaii for pleasure and that I should "keep an eye out for him on Thursday nights". So he basically spelled it out for me without saying anything.
He was picked up by a driver's service and taken to his hotel."