Anyone really figure this one out? I've got a very similar problem:

New Macbook running OSX Snow Leopard. Connects easily via my wireless network, communicates with the PC and it's two external HD's. Only problem is printing. in the system prefs/print & fax window I've tried adding printers via the "default" tab (obviously nothing there). Under "IP" I've added it under "Line printer daemon - LPD" with a valid address and name where after "gathering printer info" it lists it as a "generic postscript printer" - I change it to Canon MP600 driver and click "add" and a window drops down for a half second saying "determining installable options..." then nothing - won't let me add it. Same thing under "Internet Printing Protocol - IPP." Finally, under the "windows" tab, it allows me to add it successfully but nothing happens when I print (the queue says it printed but it never completes). I can't communicate with it via the "Options & Supplies" either - say's "gathering info," then "No info available." I've tried using the OSX canon driver, I've installed both the latest canon driver for it and the "cups" driver - no luck.

I've tried adding printers via the "default" tab (obviously nothing there)

Not too obvious for me. Like I described above, if the printer drivers have been installed (like maybe, if not included in Leopard by default, then by connecting the printer through USB first) then, when it is in range and the firewall allows access, it should show up after a few seconds. At least, for an iP4000R. See also Super User for a screenshot.

The MP600 drivers from the Canon website have the same version number 10.26.0.0 that works for an iP4000R.