According to this new post on Tobias Schlitt's blog, there's a conference happening in his part of the world, FrOSCon, who's issued a Call for Papers.

The FrOSCon (Free and Open Source Conference) is organized by the Computer Science faculty at Bonn-Rhein-Sieg. It will be happening the 24th and 25th of June with two of the local usergroups setting up a PHP room for all attending PHP enthusiasts.

For more information on the conference or on their Call for Papers, check out their site.