Select image, press Ctrl+Shift+Left or Ctrl+Shift+Right - nothing happens. Rotation works fine by clicking through the menu interface. Reproducible: Always Using Ubuntu 12.04 with Unity in case that makes a difference.
Not reproducible with 2.6.0-RC release. In fact, Rotation tool have been rewritten in digiKam core (previously, it been a kipi plugin). Gilles Caulier