Paul Lamere and Oscar Celma did a wonderful job presenting the recommendation tutorial. I wouldn't be surprised if this turns out to be my personal highlight of ISMIR 2007. They presented an overview of all the standard techniques used for recommendations, they talked about the typical (and unsolved) problems recommenders face, they had plenty of examples, and they also presented results from an evaluation of recommenders. The parts I personally liked best were the in depth analysis of tags and folksonomies, the part they called "novelty and relevance" (with interesting ideas on how to reach deeper into the long-tail), the analysis of artist similarity networks, and the evaluation of recommenders. They also made an interesting point about how nice it would be to have something like a Netflix competition for music recommendation. I'm guessing the slides of the tutorial will be online soon. I highly recommend having a look at them ;-)
I only attended the recommendation tutorial, but I've been told the other tutorials were also really well done. Seems like this year's ISMIR is not only the best in terms of number of papers submitted, number of people attending, best location ever, but also best content ever! ;-)
Btw, Paul's blogging about ISMIR in case you haven't noticed yet. And a number of pictures have already been uploaded to flickr tagged ismir2007.