I just got back from the EuroClojure 2012 conference. I won't try to summarize all the talks here, just convey some general impressions that I got:
Clojure community is awesome. People are incredibly nice to each other. Ask a question on the mailing list, and you'll get a number of replies from people much smarter and more experienced than you. Same at the conference: you can approach anyone and expect to get great advice even if the competence gap between you and the other person is comparable in size to the Grand Canyon.
A lot of the talks focused on how to approach difficult and complex real-life problems better. Those weren't talks about syntactic sugar, "best practices", or new "features" the language should have. Instead, speakers presented results of months of thinking and experimenting: new architectures, new approaches, new ways to think about problems. If semicolons were discussed, it was a discussion about how to preserve them while doing source-code transformations. This is incredibly important: you can't overestimate the value of listening to smart people talk about ideas they thought hard about and developed for many months. I had several "aha!" moments where I suddenly saw that the architectures I developed were a poor-man's subset of a more general solution.
There was a focus on building real systems. I'd say that hobbyists and academics were in the minority: most people were there to learn how to better build code that makes money. It was also interesing to see the range of sizes of companies that use Clojure: from one-person consultancies through startups and small web-development shops, all the way through large financial institutions.
The median age of participants was probably between 35 and 40 years. This is clearly not a bunch of teenagers, but rather a group that gained significant experience in various languages and then moved on to Clojure. I think this has a lot to do with my first point — the community is both incredibly nice and mature, which often go together.
Overall, the conference was a success — more so than I expected. The organization was nearly flawless (not an easy task, I know, so hats off to Marco Abis). And it is now very clear than a European conference about Clojure is necessary. I'm looking forward to EuroClojure 2013!