Sometimes, I actually ask to see the task tracker and ask which kinds of things I'd get to work on. That at least lets you know if there is interesting work that management has requested.
I always ask "if I started this position today, what tasks would you assign me?" It's a really informative question.
You'd better ask "It I started this position two months ago, what kind of things I'd be working on by now?" It takes a little to accustom yourself to each work environment, and a little longer to get into the flow of the place (know your collegues, the work process etc.). That said, yours is a darn good question, and on my next interview I'll be certain to ask it.