Some "hi-beat" watches tick 10 times per second (still well below 60). Seiko's Spring Drive (http://en.wikipedia.org/wiki/Spring_Drive) offers continuous movement, but it's not completely mechanical (a quartz oscillator controls the escapement). I would rather have one of these than an Apple Watch: https://www.youtube.com/watch?v=8m-5YpNUwgc

(Edit: only now have I noticed it was already mentioned in another comment)