chochajin wrote:
As you live in Japan, too, I guess you have a Japanese ipod touch?
Can I jailbreak ANY ipod touch? Sounds complicated, but if other people can do it, then why shouldn't I, right? 
Yeah, I have a Japanese iPod touch. Jailbreaking is pretty simple - find the right app, read the instructions, run it.
Oh, and would I need internet connection to be able to use that anki version or is it only that I need an internet connection to get the whole hack thing done once?
You need wireless access to a) install Anki on it and b) to copy your deck back and forth or synchronize. Since the client doesn't support adding cards yet, only reviewing, if you don't have intermittent access to wireless so you can update your deck, it's not very useful.
If I want to watch movies etc. on an ipod do I have to "decode" normal video files first? I have read something about ipod-format movies.
Outside of my area of expertise I'm afraid - though there's probably some video player available.
With a zaurus I would be able to run a somewhat "full" anki version, right?
The same backend runs on all versions of Anki. But each platform provides a different GUI toolkit. The Zaurus only provides qt3, so it's not possible to run the desktop client on a Zaurus either (nor would you want to - it'd be too slow!)