Excellent thread and work; very helpful. I had explored the same about a year ago and the following has worked for me several times after performing clean Ubuntu installs including Ubuntu 10.10. I too have a Canon MX860 configured wirelessly. The procedure is similar to the original post, just slightly simpler:
Go to the Canon site in Australia and download the Linux debian driver for the MX860. After unpackaging the compressed driver:
1. First, install cnijfilter-common_3.10-1_i386.debUsing the procedure above, both the printing and scanning functions work for me on the MX860.
2. Second, install cnijfilter-mx860series_3.10-1_i386.deb
3. Restart Ubuntu
4. System -> Adminstration -> Printing -> New
It should search for and find the Canon- MX860 printer as a Network Printer with a device URI that looks like: cnijnet:/00-1E-8F-72-E6-2H