I had a good time at this in London yesterday - some interesting talks in the morning including one about Linux Capabilities which I'll definitely be lifting some ideas from, and a couple of my questions ("Why don't developers and sysadmins like each other?", "What did you do with your Raspberry Pi?") were discussed in the afternoon.
I thought I'd be in a minority as a developer, but in fact it was about two-thirds dev and one-third sysadmin. Some of us considered ourselves both, of course.
Unfortunately I was feeling quite wrung out after a long week and decided to make a dash for the early train home, but I'll definitely be back at similar events in future.