You are correct.. they do not.
The idea of writting on the display like a sort of telestrator or e-paper (the Plastic reader) is interesting.. but I just want to be able to keep notes.. Alot of times in my books.. I note important areas (Flags), write notes of examples I've tried and work (psudeo code) so that I remember when I Come back..
That and pdf's like Iv'e said are important.. I have a DX in my cart.. but now let's go down another road.
How well does PDF support work in 2 vs DX.. I'd much prefer the cheaper of the two
who wouldn't. But if I can't read the Text, as in the Sony 505, it's unuseable..