I think first we should have a stable version for PC before porting it for other devices, but if you are able to do this, you can do it.

Clonk will most likely need a lot of RAM and ressources. Clonk Planet was once ported to the GP2X (but Hazard lags a bit :/ ).
If newer portable devices have more power, you can look for a person that is able to port the stuff or do it yourself (since it is open source now) :)

I dont think it would be problematic to port it to a pocket pc since the most modern pocket pcs use a leightweight linux as OS. It is may possible to play it yet...

iPhone!

I have looked into NDS homebrew developement, but I'm quite sure that more or less a 1:1 porting is impossible. The DS itswelf just has not got enough power for anything complex, it would need complete programming. Also a c4-compatibility would be nearly impossible I imagine.