I started the Chip DOS thread last year after doing some preliminary work with reading SD chips, I haven't tried writing to them yet, but it can be done.
I haven't worked on it since build-season started, but there is a bunch of info on a blog I started here:
http://www.techranch.com/blog/
I hope to create a small code library that will make it easy to interface this with the RC, but this project is on a list with others... ;-)
Thanks,
Jim