I like this UI style, and clean code. Good work!
We released as somewhat popular iPhone-based "springboard" like clone a while back on GitHub (https://github.com/fieldforceapp/openspringboard) and have since gone on to iOS6 and the iPad. The code isn't anything to be proud of.
For our iPad app, instead of your side bar style, we use a top bar with the ability to slide it down when needed, an hide it when not; the content is wrapped in a UIScrollView of buttons for the various options, using a simple highlight to indicate the selected option. You can find some screenshots on our website or in the app store description of our iPad product.
Two questions for you: how about extending your code for both side-bar and top-bar orientations? And related, can the CKSideBarController be hidden?