"There is an intriguing, mysterious gap between the fourth planet out around 55 Cancri and the Jupiter-like planet that's far away. In that gap, we don't know what there is. Our current technology would be able to detect big planets like Neptune, Saturn and Jupiter. We don't see any of them. So if there are any planets there, they must be smaller, the size of the Earth. In fact, it's a little hard to imagine that there's just nothing there in this big gap. So the suggestion is there might be small rocky planets, like Venus, Mars or Earth."

- Geoff Marcy

http://www.nasa.gov/audience/formedia/telecon-20071106/clips.html

Who knows, there may be an asteroid belt there as well.

It is interesting to note that unlike our solar system, in 55 Cancri there are gas giants very close the star. Not uncommon for extrasolar planetary systems, I know, but it does make ours rarer indeed. I'm sure celestial mechanics has a lot to with it.

I don't know about most of you, but, I never thought we'd be talking about exoplanets in my lifetime. :}