I absolutely love tmux and use it everyday, but the killer feature I really want is tighter integration with a terminal emulator like iterm2. I would love to be able to attach to a tmux session with iterm2 and scroll using two-finger scrolling, while still being able to detach from the session and re-attach remotely.

It would seem like this would be a possibility given tmux's design, which is a lot more flexible than GNU screen's.