It's now two years later, and few publishers have followed in the footsteps of Baen Books, Tor/Forge, or the other handful of US publishers who have dropped DRM or simply never adopted it.
Even though Tor UK said in April 2013 "we’ve seen no discernible increase in piracy on any of our titles" as a result of dropping DRM, many US publishers are still wedded to the idea of treating their customers like pirates. This includes Amazon, which insists on using DRM on audiobooks.
Luckily the same cannot be said for other parts of the world. In Europe there are a growing number of publishers who are choosing to use less onerous forms of DRM or go DRM-free. Some of the alternatives include digital watermarks from companies like Booxtream, ePagine, and others.
Pottermore, for example, uses digital watermarks for the ebooks they sell.