There are two different angles that I see here, there is the angle of Paleography or the study of handwriting, and thus digital paleography, which has been discussed on the Humanist list which is an old digital humanities list that is still quite popular. I only know of one or two people doing this work actively. then there is the question of studies of rhetoric, composition, research practices, etc. etc. that go into the modes of productions of the work, and those are huge well established fields that have been around since the 1950's. Though the modes of research is less popular by far than the other two, there is a book every few years that considered aspects of that. so Ipads... I don't actually write on mine, i do compose music sometimes, but I don't even use it to answer email unless it is my only option. I'm as such wondering about what is really changing and where with respects to pad culture, whether ipad, or not, and 'writing' . I used google scholar in the humanities and social science side and put in ipad and composition, and found.... quite a bit... too bad i have to go back and finish like 8 other projects before i can allow myself to get curious about another:)