This is great. There are lots of books that fall into this category and would see a lot more use if there were available digitally. I'd love them for myself, but I can also imagine assigning them (or parts of them) more frequently to my students. Also great is that the program insists that the books be released in the EPUB format, which is open, looks good on lots of readers, and makes it fairly easy to get the text out.
Regarding that last, a potential limitations that I hope we don't actually see too much of results from the program's lack of a specific requirement that the work be re-usable. Instead what's required is a CC license. Any CC license. That means that in reality there's no guarantee that it will be possible to reuse the work (apart from the usual fair-use ways). I tweeted this question and @NEH_ODH replied quickly (love those guys):
@NEH_ODH Great news! Will there be ability to freely make derivative works too?
— John Muccigrosso (@JD_PhD) January 15, 2015
@JD_PhD It depends on which CC license the publisher chooses. But generally, yes.
— NEH Dig Humanities (@NEH_ODH) January 15, 2015
So let's hope that lots of publishers do make the choice to allow such re-use. I'm worried about it in part because we know what publishers can be like. On the other hand, the program explicitly solicits applications from more than just presses: "scholarly societies, museums, and other institutions that publish books in the humanities," and these groups might be a little more inclined to use a more permissive license. A little outside pressure might not hurt either.(If @NEH_ODH would like to comment, I'd be curious to know why they didn't impose a more open licensing requirement. Worried that publishers might not respond so openly?)