Shotwell rocks ! Congrats to Yorba and his team.
I have a small issue with Shotwell 0.9.3. When selecting specific "Events" or "Tags" (in the left bar), the photo's appearing in the main window do correspond with the selection but are no longer ordered in accordance with the order selected in "View", "Sort Photos". This can be confusing.
For obtaining the visualisation of the photo's in the desired order, I need to change ("View", "Sort Photos", ...) the order (into an undesired order) and then immediately reselect the original (desired) order. I suppose that after selecting a "Tag", the Shotwell code may have to automatically launch an ordering instance.