Is it time to refinance?

SayUncle mentioned that interest rates are so low, the money's almost free. I wouldn't go that far yet, but it does seem that now is the time to refinance your house if you need to do so. He has a poll up asking people if they are refinancing. I won't steal it but you can go over and take a look. So far, over a quarter of the voters say they are waiting. I think the time to refinance might be when it hits 4%. What do you think? Is it better to jump in now or wait and see if the rates drop?