http://omeka.org/codex/Plugin_Use_Cases/Add_a_New_Output_Format
This seems to be outdated. The examples don't work for Omeka 2.0. Can you clarify what changes would need to be made in order to get a new output format to work as a plugin for Omeka 2.0? Thx.
As a rule, developer documentation on the Codex is for Omeka 1.5 and below.
The new documentation doesn't have an equivalent copy of that page, but the main differences should just be the names of the filters: they're now action_contexts, response_contexts.