They're not giving up on DRM entirely, but they have indicated that another 8,426 ebooks will be available protected only by digital watermarks. Counting the DRM-free titles (both Epub and PDF) this means that nearly three-quarters of the 20,000 ebook distributed by CB will either have no DRM or have so little DRM that the average user likely won't notice.
CB is describing these 74% of ebooks as being DRM-free, but that's not quite the case. First, there's no guarantee that these ebooks will be DRM-free when sold through the major ebookstores (Kindle, Nook, iBooks), but of course we knew that. Also, the 16% of titles carried by CB as truly DRM-free are more likely to stay that was when sold via the major ebookstores.
The more important detail here is that there is a difference between having no security and having some security. Digital watermarks still provide a measure of control. While they don't get in the way of a paying customer, they can still be used to identify who originally bought a piece of content. That can be useful data should an ebook, mp3, or other content show up on a pirate site.
This deal mainly affects the smaller ebookstores which work directly with CB to stock Dutch titles (because digital watermarks need to be applied at the time of download).