I usually grab ideas, webpages, documents, etc., into Evernote in order to prepare some material for my classes.
As a part of this, I write a first note with the purpose of that notebook and the list of projects that should be done with that info. It would be very useful if I could pin this note at the top of the notebook so I can always focus the work on that notebook on those tasks and projects, otherwise it happens that this note is buried by any new webpage, article or else that comes to that notebook.
In summary, pinning a note on any notebook is a very useful feature that can enhance Evernote. I hope other users think the same and can promote this as a feature to be included in a nextcoming version.