The EPub plugin (net.sourceforge.dita4publishers.epub) generates electronic books in IDPF epub format. These ebooks can be read by most eBook readers, including Adobe Digital Editions, Stanza, and others.
The content of the EPub is HTML as generated by the normal Toolkit HTML generation process, which means that any HTML extensions integrated with your Toolkit will also be used to generate the EPub content.
The EPub plugin supports generic maps, book maps, and publication maps.
If you install the full set of DITA For Publishers Toolkit plugin then you get the EPub plugin automatically.
You can also download and install the EPub plugin separately from the DITA For Publishers download area. Simply unzip the dita4publishers_epub.zip file into the plugins or demo directory of your local Open Toolkit installation and run the integrator Ant build file as explained here: Installing the DITA For Publishers Package.