Wow, GDC was such an overwhelming experience! Keep in mind that I was absent for 4 years and, since then, it became even bigger than it was. I could not attend to many talks since I had quite a bunch of meetings with clients and publishers, but I was lucky enough to attend to pretty good ones.
I would highlight Jane McGonigal's rant, which deeply moved me. Unfortunately I think it did not get the reaction that it deserved but, at least for me, it was the first time that I heard a designer speaking straight from the heart about the importance of play itself in our everyday life. Kudos to Jane, you're my hero!
Margaret Robertson also gave an excellent talk. Her encyclopedic knowledge of games is simply amazing. She picked excellent examples to illustrate her main point, which was how designers must treat players: with love. And she did not mean this as a metaphor, but rather literally. A truly smart presentation, given in plain English and illustrated with right-on examples.
Rod Humble's presentation on The Sims Carnival was also one of the highlights of the conference. The site is still only accessible by invite only but keep an eye on it. It's an online community where players not only can create games but can also modify other people's games. I was delighted when I learned about it, since it's pretty much the same model that I proposed seven years ago in my dissertation Videogames of the Oppressed. At least at first sight, it seems like it would be a great environment for testing my theories on Boalian games (and it was developed on EA's money, which is even better :)
Raph Koster's keynote was a virtuoso technical demonstration of Metaplace. Certainly, it was much more technical than most people would have preferred, but it was amazing to see what the project is coming to: an elegant approach to MMO design where the client is designed using regular web technologies. Incidentally, Raph was one of the very few people who got a chance to take a look at my upcoming commercial project (sorry, it's still secret!) He seemed to have really liked what he played, since he even posted about it.
Overall, this GDC was particularly satisfying to me since I got the chance to meet again many friends that I had not seen for years. And I got a chance to bring Rock Band to my studio (which I'm starting to think it was not such a great idea, since I can hear now from my office some awful version of a Nirvana song... Oh, well, I guess it's just play after all :)