There isnt a dev diary/blog for the whole team, but their individual sites have a heap of concept art and production commentary. The imagery below is from these sites and reveals the amount of work put in to arrive at such a level of quality.
Maybe I need to just take a chunk of time off work so I can get right into the creation of my own concepts, just looking at these images is very inspiring - it shows lots of fun in the conceptual sense and then follow-through on more detail and then completing the project. I just wish their blogs had more images of the 3D models under construction, the render tests, storyboards and the whole bit. Their blogs are worth a visit though as there are still lots of pics to see - and nifty work by the whole team as well, not just one of the group.
[Production Images from A Fox Tale via the creators' blogs]