As you may know WordPress was intended to give anyone a publishing platform. PressBooks is a plugin that takes that principle one step further in that it allows you to actually publish a book via WordPress. Or, as they put it:
PressBooks is a simple online book publishing tool, built on WordPress. We help publishers and authors create ebooks, typeset/print-ready PDFs (to be turned into real books!), and webbooks (which can be public or private). For publishers, we can provide not just book production toolset, but also an online catalog and website (for examples, see: The Rogue Reader and AskMen Books).
It seems only fitting that a very cool solution on top of WordPress finally goes one step further and becomes open source project. Their idea is to turn their business into a freemium model which seems to be doing very well for WooThemes with their WooCommerce for instance.
So what do you think, is this a step in the right direction for PressBooks?