The reason why I'm interested in the Drupal Commerce module is that I worked on Magento and Drupal integration for OCentric at my previous company (Optaros) and I've seen how difficult it is to have content, community and commerce mix in one solution. Therefore Drupal 7 + Drupal Commerce mix looks really promising. Just think about having a piece of content and adding a "product field" to it, formatted with "Add to cart" button; or the opposite - take a product page and add a piece of content to it as a field, which can have its own comments, ratings, etc. Really flexible and powerful!
One sentence by Ryan got imprinted in my brain:
"Ubercart was the first PHP and MySQL project in my career, so you guys are pretty brave to use it in production"
Another session that stood out was the keynote by Rasmus Lerdorf, the creator of PHP. It really corrected the way I look at PHP. He also showed some tricks for debugging and tracing the performance problems for Drupal. It was pretty impressive how in 15 minutes he spotted that the bottleneck in Drupal is the rendering engine which he suggested to rewrite in C/C++.
One sentence by Rasmus that imprinted in my brain (with some distortion):
"PHP has always been a templating language. All the heavy coding must be done in C"
The session on Varnish was probably the geekiest of the ones I attended, but Paul-Henning Kamp (the creator) made his point - you have to use Varnish!
And I was totally impressed with Aegir, how come I've never stumbled upon it? There is no doubt that this tool combined with drush_make will save the world from the Drupal deployment hell.
All in all, there was quite some buzz about Drupal 7 during the conference, many serious modules are developed directly for 7.x. This is mostly due to the fact that 7.x has this concept of entity (a field) as opposed to nodes/comments, which solves a lot of problems. I'm really looking forward to Drupal 7 and all the goodies that'll come with it.
This was my first DrupalCon, and I must say that the crowd was really amazing. A bunch of friendly and easygoing people.