I'm having trouble with the file. I ran an md5sum on it and got:
-rw-r--r-- 1 me... mine.. 735832064 Jul 21 22:12 ubuntu-8.04.2-desktop-i386-sheevaplug.iso
When I check the actual iso, I find that three files don't match the internal checksums. Two of them are manifest files and should not matter.
Indeed, but if you diff them on the CD you'll find that they do not differ, so why would they have diifferent md5sums (which md5sum.txt claims)?
The third is ./casper/filesystem.squashfs. I'm sure that does matter.
Given that the other files in casper/ are wrongly listed in md5sum.txt, I'd assume that it is the list which is wrong.
I was unable to burn a cdrom of the iso file. I suspect that it is just a hair too big. I burned it onto a USB key instead.
2 -- Has anyone actually successfully booted from this disk?
Sort of. I'd actually burnt it to a DVD (I needed an iso image for a test and knew where this one was, so used it. Just tried it for you and it certainly booted (I'm now looking at a heron on my laptop).