Wow. A book. With links. Why didn't I think of that?
Why isn't a television show called a "video novel"? Why isn't a movie called a "celluloid novel"? because there are significant differences between reading text and watching video.
To me, this shouldn't be called a "digi-novel" at all. It is a multi-media story or presentation, part novel (or is it novel, if the text itself does not convey the full story?), part video, part web, part whatever else you want to throw in there.
Penguin is obviously trying to revive the reading public's interest with bread and circuses. Me? I'd prefer they find some good stories to tell, and people who can tell them.