Installing Debian in a blueberry iMac DV is a highly enjoyable experience everyone should try. If you're a clueless newbie (like me) it may take a few hours, but it may be fun even for more experienced users or for people that played with an iMac before.
First of all, BootX won't work in the DV (after a few frustrated attempts, you come to that conclusion), so you'll have to use yaboot. The installation procedure is simple: just get the installation kit of LinuxPPC and the Debian base system tarball, boot using the provided ramdisk image, create some files in /dev, make the partitions and filesystems, open the tarball, do some minor configuration and presto!, you're running Debian!
Except that the LinuxPPC installation disk doesn't include tar. It can't mount NFS volumes read-write. But that's a minor hassle because you can repackage the tarball with cpio, no problem.The boot partition must be HFS. fstab must be created by hand. And the worst part, you must know that, after entering Open Firmware pressing apple+option+o+f, the command to boot yaboot is boot hd:X,yaboot.tbxi where X is your partition number.
BTW the reset button if the iMac is concealed in its side, disguised as a "play" button.
I wish I had the user's manual.