FrOSCamp is a multilingual two-day event taking place on the premises of the ETH Zurich in September. It is completely free of charge and no preregistration for visitors is required. The event consists of an exhibition, talks, workshops and hackfests featuring free and open source software, free content, open standards, open systems and digital sustainability. People and projects are invited to demonstrate their work and to explain visitors said topics.
http://wiki.froscamp.org/Welcome
The Linux Kernel Summit brings together the world's leading core kernel developers to discuss the state of the existing kernel and plan the next development cycle. This two day conference is invitation-only and focuses on development and innovation through sessions and workshops that encourage interaction and discussion between kernel developers and industry leaders.