Also Can't Find on Canon.com
Martin,
You're not crazy, I looked on the usa.canon.com download index, entered my camera, EOS 5D Mark II, and had a bunch of updaters (you need the original CD) for all their software but PhotoStitch! Luckily, I keep all my boxes and junk and dug up the Canon SW CD, which has v3.2 on it. I don't know what the latest version is, but I got it, and I'm apparently stuck with v3.2. 🙂
David