Have to say, the most intriguing ideas I saw in the concept were the two "split view" concepts - one for managing blog posts, and one for writing posts.
Has any blogging platform implemented anything like that? I know there are Markdown editors with a split view, but I don't know of any that are web-based, nor any that are integrated into existing blogging platforms. And I've definitely never seen any "manage/edit old posts" system as clean and simple as the one in the concept.
Oh, and btw, a brilliant concept that's super easy to miss - being able to type "(image)" in the editor pane and seeing an image upload placeholder in the preview pane. It's a small thing, but one of those things that seems way more obvious than it actually is.
From an aesthetic point of view, I'd really want the Markdown code to be more visually distinct from the preview.
I'd love something like the "Oblivion" colours in gedit for instance, although I am aware that opinions differ on dark backgrounds :) It would give a nice visual distinction though, like the old "underwater" mode in WordPerfect.