Why the delay? If you know Malick at all, you know the answer to that. The film is not yet finished. The Tree of Life has already been a 30-year journey for Malick, and another year (or two, or three) won't make any difference to the notoriously meticulous director. No one has even seen the film, or knows what form its final cut will take. All that's really known about the movie is that it's a family drama that spans the 1950s and deals with the loss of innocence.
Apparition Films remains optimistic that you'll see the film in 2010. It won't make Sundance, but it's likely to make Cannes. (That is the film festival that belongs to Pitt and Angelina Jolie, so fate would dictate that's where it would premiere!) But even that is up in the air, as Berney admits he has no idea when the film will be finished, or when it will be released.