Below are a list of books associated with KDE 4 development. These may be specific to applications, using the Qt Toolkit, or specifically KDE 4 books.
In general, IRC channels mentioned here are available on FreeNode. Connect to irc.kde.org, and check these channels out for further information.
KDE 4 Development - #kde4-devel KDE Development - #kde-devel KDevelop - #kdevelop Phonon - #phonon Decibel - #decibel Solid - #solid