Two years later:
The Magazine, Newsstand, and "Subcompact Publishing" all turned out to be duds.
Ebooks may still be relevant for now. But the medium is so annoying to work with due to platform fragmentation and complete lack of open distribution mechanisms.
Personally at this point the mediums that interest me most are (1) plain old web pages (for reasons like this) and (2) printed books (which, unlike any digital format, have actual archival qualities).