Agreed - although Ember Data is working well for me, I've found the lack of documentation to be a productivity sink. Too often, I have to get into the code to find out how things work (even to get a list of possible values for DS.attr(), for example).
I'd love to know where I can contribute to the docs, so I can help update them as I learn things.
I've also seen some tweets to suggest that ember-data is getting a lot of love this month.