I often use Google Docs for collaboration with a range of parties. My question is therefore regarding information safety. In the cases where I am not the owner of a document, how can I ensure that the owner does not remove me from the sharing list, meaning that I can no longer access the information that I contributed to?
I would say don't assume anything and backup. Even if there was a way, you never know when Google (or any services) will change there mind on how things work.
I am personnaly using Backupify to backup a lot of my web services.