In the past we've already talked about features/changes for digiKam 4.0 and the work keeps piling on with this weekend's 4.0.0-beta4 release.
Among the changes to find with digiKam 4.0 Beta 4 is a tool for organizing whole tag hierarchies, a new maintenance tool to parse image quality and auto-tag items using Pick Labels, the Showfoto thumb-bar has been ported to Qt Model/View, improvements to the impoprt tool, and the release is now fully ported to the Qt4 model-view with the last of the Qt3 support classes having been dropped. The digiKam developers are planning to move to Qt5 at some point in the future.
Planned next is to have a digiKam 4.0 release candidate in mid-April and to do the final digiKam 4.0 release around 11 May in conjunction with KDE SC 4.12.3.
More details on this latest development version of the digiKam digital photography software can be found at digiKam.org.