KDE has a number of sub-projects that have blossomed into enormous projects of their own. A number of them, such as KOffice, or KDE-Edu get a lot of press in the open source world, while the KDE PIM project has been quietly gaining corporate acceptance as a suitable enterprise suite.
Today's feature are the libraries that power the KDE PIM project, and specifically, what changes have taken place since KDE 3.5.x, wherein the KDE PIM project is one of the most successful and stable components of KDE.