I've a Selphy ES20 - and now it prints.
The Gutenprint driver won't work - neither Gutenprint 5.2.3 nor 5.2.4.
I've made it nearly like zenobiaflex:
(Due to I don't now what the best way is, I write down my steps)
1.) Installed Gutenprint 5.2.4 = don't print
2.) Installed the Canon ES20 printer driver 2.1 from Canon Website (although it's not for OS X 10.6)
3.) Deinstalled Gutenprint with "gutenprint-uninstaller-1.2.6.dmg" (see
http://gimp-print.sourceforge.net/MacOSX.php)
4.) Reboot the Mac
5.) After reboot, the Mac finds the Selphy by himself and can print (under iPhoto, Photoshop Elements and so on)
After all: I hople like zenobiaflex that Apple or the Gutenprint-Project recognize that the driver is completely useless (more tests before approval?).