It's just very rare to see a Ghibli cel and its 
background together. Has to do with the fact 
probably they aren't released like cels from 
other series. In fact, it's rare to find other 
production work with a Ghibli cels (no sketches 
are packaged together with the cels in other 
words).

The only digitally done work on Mononoke -- can 
be found at this page:

http://www.nausicaa.net/miyazaki/mh/cg.html

About fifteen minutes were digatally done.

Wendy