Folks have been asking for details ever since my happy tweet… Until this all gets automated, this process should work if you had already set up your Canon wireless printer/scanner under Mac OS X 10.5:
1. Reinstall the 10.5 versions of the IJ Network Tool and the printer and scanner drivers posted on Canon's site. You will end up restarting your machine 3-4 times.
2. Instead of running the auto-installer from the disc, open System Preferences and choose Print & Fax.
3. Add a new printer to your list using the "+" sign. When the selector appears, choose "IP." Change "protocol" to "IPP" and select "More Printers" in the lower left hand corner. Your MP620 should pop right up in the list. Select it, and you're back in the wireless printing business. IJ Network Tool should already be running in the background and take care of the scanning for you.
Officially, Canon says they should have a 10.6 version of the automated installer by mid-September.