As this new post on the symfony blog points out, their next Plugin Developers Day is happening this weekend on Saturday, November 8th.

Preparations for the coming plugin developers day on Nov. 8th are proceeding apace. I've heard from a number of you who are planning to attend, some planning to start development on new, groudbreaking plugins, others looking to help update existing plugins to work with the latest and greatest version of symfony, and still others just hoping to learn from the lively discussion. All types are welcome!

The event will be centered around the #symfony channel on the Freenode IRC network and is broken up into different sections - creating and releasing a plugin, writing a customizable plugin and coding sprints on new/existing plugins.