I don't use the Notebook, and yet there's an icon for the Notebook at the bottom of the screen in the Toodledo iPhone app. I can think of many choices that I would prefer for that prime screen location:
2. Starred items
3. Next Actions
5. Recent items
6. Orientation lock
I'm sure that there other choices that some users would prefer over Notebook.
How about allowing the user to specify what shows up in the taskbar?