Yeah Bob,

They are drawing off the same genre tradtions. It might be possible that Rowling used some of the same devices as Pratchett (real witches dont get burned, talking wizard hats that sort of thing) and even had the ideas sparked from him but it is hardly stealing. The similarites are minimal, and because of the nature of l-space, a little overlap is inevitible.

I recently read "Hat Full of Sky" and loved it! He is really building Tiffany's character fast and I cant wait till he writes the next one.