Remove DRM from ePub Files?

Some guy with a blog called "I♥CABBAGES" seems to have reverse engineered ePub DRM, and some other guy wrote a detailed How-To guide here:

Free epubs from Adobe ADEPT DRM

Which refer to scripts you can find here:

Circumventing Adobe ADEPT DRM for EPUB

Note: If you get the error: "Not an ADEPT EPUB", then your ePub file is missing the META-INF/rights.xml file in its archive because it probably wasn't downloaded from the publisher correctly. Here's how to resolve the issue:

1. Re-download the book from the store you bought the book from and observe that you just get a .acsm file instead of a .epub file.
2. Instead of inspecting the contents of this .acsm file to get a link to a .epub file, you will have to open the .acsm file in Adobe's "Digital Editions" software (which is a horrendous piece of crap, by the way).
3. After opening the .acsm file, Digital Editions will put a working .epub file in My Documents/My Digital Editions on Windows. It probably does something equivalent in MacOS, use your intuition to figure out where it might put the file.
4. Run the scripts mentioned on the Circumventing Adobe ADEPT DRM for EPUB page on this .epub file.

There is also a method specific to Barnes & Noble:

Circumventing Barnes & Noble DRM for EPUB

There is a blog post with tools that worked for me:

DRM Removal Tools for eBooks

It has updates to original tool from "I♥CABBAGES" and also plugis to Calibre.