It's odd that our angry chinese poster (i guess it's kinda obvious, right?) turned against one of the devices with most promise in this field. First, adding interface text is pretty easy, just look at the desktop distros of linux, where you can easily select swahili if you must. Since maemo does support localization in some languages, i see no reason why other language packs (including chinese) shouldn't be easy to install.
Now, input is a very different thing. I know little about asian languages, but i'm quite sure lots of them use hundreds (even thousands) of symbols. Now putting them all on a keyboard would be a pain. On screen keyboard would also be pretty difficult. Sign recognition would be obvious. That works how on iphone? At least the n900 has the technical ability to do this, only some software needed.