Hm, well, I've only recently started playing the violin, and I don't think it's easier for me because I'm a pianist, it's rather because of the fact that I'm a good musician with a "good ear". So that makes it very much easier and faster to learn.
One thing I used to find confusing is the fingering -- index finger is 1, because thumb is not used. It used to drive me nuts when I'd try to play my violin music on the piano, because I'd instinctively try to follow the printed fingering.