We haven't seen any except one scripted sequence in Cloudbreather's Crag, which only lasts around five seconds.
(Though in the sense of the on rails game mechanic only- you just jump flawlessly through airships. Actual rail grinding, no, we haven't)
--- Power is the thesis (power, power) Crimson on my lips, when I smile I'm a t-rex
Edited 2 times - Last edited at 11:32:08 02/09/2015 by Bifrost