A roll up screen isn't really practical in a useable device and how would you write on it?
Personally if someone came out with an A5/Moleskine sized device that let me write notes/articles, draw quick diagram's, add calendar entries, send & get email, surf the web and participate in wifi networks -- I would shell out $1000 easily. An electronic notebook/Moleskine/sketchpad that lets me run widgets to do things like control my other WiFi devices would be near nirvana for me. Something that recognises when it gets home and dumps all the changes to the local network and picks up updates without my intervention... droool....
I've got boxes of notebooks and diaries that are dead data and a pain to use -- dead data costs me too much time -- imagine no more dead data?
Will the Newton Ever Come Back?