I watched a lot of interesting talks (and I'm still catching up on the talks I missed via Superlectures). In particular I found the OwnCloud talk by Jan-Christoph, the Hi-DPI talk by Alexander Larsson and the Sandboxed applications for GNOME talk by Lennart Poettering extra interesting. Of course Zeeshans talk on GeoClue and Maps was very nice too. :)
I also attended the Maps & geolocation BoF. We talked a lot on how to do search, present POI's and more, but more important to me is that we decided that we wanted to give GraphHopper a try instead of OSRM for routing. This decision was made since GraphHopper has a stated goal to support GTFS import as well as OpenStreetmap (making me not having to implement public transportation support in Maps as plugins but rather as normal requests to GH), its demo server supports biking and pedestrian in addition to car and the system requirements for running is a little less ridiculous than OSRM. I've sent a mail to the GraphHopper list to start a discussion on how I can help there but apparently the main developer is on vacation so I'll have to patiently wait for a little bit.
Other than that GUADEC was of course also a very social event and it was very nice to be able to talk in person to all the people I usually interact with on IRC or Google+.