In many museum galleries audio-visual devices are unmanaged. They are controlled simply by cutting the power at the end of the day. Video monitors, DVD players etc have no problem with this.
Any general purpose computer, regardless of operating system and including the Raspberry Pi should be shut down gracefully to reduce the risk of file system corruption.
For reliable long-term use in museum exhibits where graceful shutdown is not practical the use of a read-only file system is one tactic that can be employed.
At LCA2014 I reached out to the open-source technical community for their thoughts on this problem and am grateful to the many delegates who subsequently offered advice.