The California Campfire Permit has been a piece of paperwork that somewhat mystified me. Free but you'd need to visit a ranger station or fax them to get one.
Now you can obtain one by taking the "test" here:
http://www.fs.fed.us/r5/sequoia/passesp ... index.html
At the bottom of the page is this link to the permit:
http://www.fs.fed.us/r5/sequoia/passesp ... it2010.pdf
As far as I can tell, print it out, sign it and you're good to go.