Why is this surprising? If we're using gravitational anomolies to detect planets, of course it's going to be easier to find large planets that are close to their sun, because the effects of gravity are much greater.
Ding Ding Ding! We have a winner!
It's called a "selection effect" - the data sample looks biased towards hot Jupiters, but that's only because current detection technologies find those preferentially. Give it about 10 years and we will have much better data with the new surveys coming on line. Anyway, personally I find it amazing that we now know of 10 times as many planets OUTSIDE our solar system as IN it!