According to the announcement posting, besides having a bunch of bug fixes, this new version also introduces some new features such as:
- Progress manager to control all parallelized process running in background
- A new Maintenance Tool have been implemented to simplify all maintenance tasks to process on your whole collections
- A new tool to export your collections to ImageShack Web Service
- Porting to LCMS version 2 color management library
- A new tool dedicated to manage colors from scanned Reversal Films
I have added two additional packages on my SlackHacks, OpenCV and Lensfun. OpenCV is required to compile digiKam, so i suggest you download and compile them as well. It has been updated to the latest version, 2.4.1. Lensfun is an optional package, so it's not mandatory.
If you ever wanted to get the full features of digiKam, i would suggest you to have a peek on the README inside the source. You will see a list of extra components that are required to get more features, such as Face Detection, Geo Mapping, and many others.
Update: (June 10, 2012): I have added some notes on the README about the requirement to compile digiKam. Basic requirement that you must met to compile digiKam 2.6.0 is libkdcraw that is part of kdegraphics library, ffmpeg, OpenCV, and QJson. The last four are optional dependencies.