After 6 years of absence, I participated again in a KDEPIM meeting, to fix some issues in Akonadi in order to improve my daily life :-)
Here's a report of what I did:
Fixed: "incomplete collection" error in mixedmailresource (bug 285973)
The first two with the help of Kevin Krammer, the other two with the help of Kévin Ottens. I would not have been able to fix these bugs without their input, which shows the usefulness of in-person meetings.
Also implemented some new debugging helpers (clearing the database cache for a folder, in akonadiconsole, and new methods for dumping the scheduler task list in a resource).
I also took the opportunity to discuss other issues with people present there (with Kévin Krammer during a much-longer-than-expected travel time, and with Volker, thanks to the long waiting for our food at the restaurant!). Overall I had time to discuss most of the other things I want to fix in akonadi, even though the actual fixing will have to be done later:
Overall, what's very useful for a non-kdepim developer like me, forced to fix bugs in kdepim to be able to read his emails :-), is to have been able to discuss with the akonadi master-minds in order to grasp the overall concepts.