Yes, you're right, Tom. A mission statement is often a goal, something to be reached or to reach for. Yet..
Sometimes the journey is the destination! =)
Some previous threads about the discussion of OpenACS clearly show that there is a diverse set of actors:
end-users
developers
stake-holders etc.
and their goals from using OpenACS:
enterprise toolkit
specific vertical implementations
school project
personal blog
custom web app
management information services system
portal
workgroup support
hobby etc.
We have the journey in common. Many decisions have been influenced by the values associated with how we collaborate and develop the basic building blocks of the system.
The mission statement should invite and motivate regardless of how any actor views their participation or (to a resonable extent) how actors want to use the tools.