Hi there,
When SivlerStripe 3 was released, I started creating a guide on how to use the admin area to give to my clients. The guide has grown into a quite comprehensive ebook. This guide has proved really useful, and I've recently put it up on my SilverStripe Resources website.
http://www.silverstriperesources.com/books-and-ebooks/using-silverstripe-3-ebook/
As well being available direct to the website owners, if any developers are keen on getting a 'rebranded' version to give their clients just let me know.