Nice typography and a clever layout is part of the attraction, and there has been some discussion about whether the Biodiversity Heritage Library (BHL) could be integrated.
Personally I'm sceptical. For me the key to Flipboard is not so much the nice interface, but the fact that the content is timely and relevant: timely because it's taken from live streams, and relevant because it comes from sources you select, including those form your social network. BHL doesn't have any of these characteristics. It's a huge digital archive with very little structure, and what structure it does have is largely bibliographic. For this content to work in a Flipboard-like environment I think BHL would need to develop "streams" based on, say taxa, geography, or readership, and these would have to be personalised. In a sense, Flipboard is displaying streams of content assembled by a combination of editors and your social network, and BHL has neither.