To be honest, I've tried reading eBooks on every mobile device I ever had. Most of them were cell phones, and now it's Sony PSP.
And what about eInk devices, then I've been track their tech progress since lab prototypes some years ago.
Recently some magazines have been born in Russia -- "Мир фантастики" ("World of Fantasy|Fiction") and "Mobi" -- which are narrowly follow the evolution of mobile reading devices (though, that is not their primary goal).
Offtopic: It's shame, that many manufacturers disallow legally extend software components of their devices (and I didn't mean "haven't bored to give some kind of SDK", but actually block any possibility -- Sony's PSP would be a good example of such a platform). But on the other side, writing various converters for some devices was one of the funniest things that I ever had done.