This new category is going to have 25 subcategories, one for each of the sections of the iBookstore. It's not clear how Flipboard is curating the titles, but it looks like they are only grabbing the covers and whatever description was submitted by the publisher/author. My guess, after flipping through the comics section, is that Flipboard is simply pulling titles based on the best seller's list for each category.
Still, it does look very pretty, and this is bound to generate income for Flipboard, and that's always a good thing.
But as I look at this new category I can't help but wonder how Apple got the design of the iBookstore (and iTunes in general) so wrong. I'd much rather browse for content in Flipboard than in iBookstore itself because the layout is much more appealing in the Flipboard app. Considering that the entire purpose of the iBookstore is to tempt you into buying content, it should not be the less appealing option.