Mailing List
If you want to implement a new plugin, add Kipi support to a new graphic application, or just speak about it, you're welcome to join the kde-imaging@kde.org mailing list.
The mailing-list archives can be consulted at this url.
IRC Channel
You can meet KIPI developers on #kde-imaging IRC channel (Freenode).
Bug reports and Wishes
For bug reports and wishes, please use the KDE Bug Tracking System.
The current bugs/wishes list is available at this url.