Lost In Translation is one of my favourite movies of all time, and certainly my no. 1 of the last decade.
Some dude has done some work to clean out the background noise to detect the previously unknown snippet which the Bill Murray character whispered in Scarlett Johansson's ear during the final scene of the flic. Do not click if it's going to spoil the ending for you. Here it is on Youtube. Look and listen.
A mystery solved.
[ pointer from Kottke ]
You may also like to know that the result from the audio analysis is NOT the line in Sofia Coppola's shooting draft script for the movie.
And here's a verbatim transcript of the movie dialogue. Of course the inaudible line is not included.