Here's the first release of PBooks!
Here's a basic PBooks install guide for developers. This tarball includes nexista so you won't have to install that.
I've also opened up the PBooks SVN browser in the trac environment to anonymous users:
http://www.svn.pbooks.org/trac/browser
NOTE: This software still needs a lot of work to be made easily installable! :-) I look forward to hearing your comments, and feel free to join the forums for extended discussions.