I recently found this article that was published after 9/11 regarding cleaning objects covered in dust and ash. I freely admit that the kind of dust and ash mentioned in this article is NOT the same as the ash after a wildfire, but it might give you something to start with.
http://www.heritagepreservation.org/PDFS/Dustpressrelease.pdf [acrobat required]

Here is a video on returning to your house after a fire and cleaning objects:
http://www.heritagepreservation.org/video/HPsoot.html

Other links for cleaning fire damaged video tapes, photographic and audio materials can be found at:
http://www.nfsa.gov.au/preservation/care_audiovisual/fire_damaged.html

An article from Stanford University about recovering objects after a fire. There is also an interesting section on what smoke really is and how corrosive it can be. This was written for institutions such as libraries and museums, but the explinations can be translated to the home. This article is especially helpful because it talks about clothes (in the form of costumes), wood furniture, upholstered furniture, books, paintings, etc.

http://cool-palimpsest.stanford.edu/byauth/trinkley/wildfire.html