From a quick perusal, it seems that Google Docs does not support version control the way git or svn does. My question is:
If I want to store all my documents on Google Docs, what is the best way to make them be capable of branch/merge type version control? What would this require?
Or what is the workflow you use to store your families/companies documents on Google Docs and sync them with git/svn so multiple people can be editing a document concurrently and they won't overwrite changes?
You can try to write an application to do that. Read some google docs protocol documentation, specially Document Revisions section. Be aware though that this is going to be a lot of work: you would need an application that compares all the data from your revisions in google docs to your git/svn ones and vice versa.
Seriously, having already a SCM configuration, I would stick to it, and do a simple python script that would "export" the last docs commits (or tags) to my google docs. This way you can read your documentation anywhere (you just need a browser) but still having the benefits of a traditional SCM, being this a best-of-both-worlds approach IMHO.