KDE 2.0 Development, a new book being published under the Open Publication License is now available online, in full, for free, at http://kde20development.andamooka.org/.
The site also holds all of the source code from the examples in the book,
downloadable HTML and PDF versions, an annotated online-only abridged KDE API
reference (Appendix B), and an annotated version of the KDE Developer's HOWTO.