Zooming UI note-taking app I'm looking for an iPhone app with which users can use the zoom in and out to write down characters in all kinds of scales.

To be more specific, if the user zooms in, the whole canvas would become larger to the user, making it possible to write relatively small characters.
Prezi.com has an iPad app, not quite what your looking for but I imagine it is the closest that exists at the moment, you could always use any drawing program (adobe has a few) and I imagine it would have zoom capabilities.