Might be late December, but that's probably wishful thinking based on my record of hitting release dates. Probably late January.
It really comes down to how many new features I add. The bad part is having to do the boring stuff like adding alpha channel to AVIs and supporting DV AVI natively. The good part (for me) is adding new features such as the looping. I'll definitely be thinking about the looping, but I'm not saying that the 3.5 update will have looping. I'm not saying it won't, but I'm not saying it will.
Since I know people will ask, I'm also not releasing a feature list yet. There are some things I'd like to add, but if they turn out to be too difficult (or impossible), I don't want people disappointed.