Open Radar

 
A very useful and seemingly-simple-to-implement feature of iBooks would be the ability to import notes. People could post annotations files that others could download. When opened in iBooks, it would prompt the user to purchase the book in question from the iBooks Store if they didn't already own it, and then import those Notes into the user's copy. That way, individuals could create and distribute annotated versions of historical or popular works without having to obtain the rights or publish them themselves. For instance, one could annotate Sherlock Holmes to explain the features of Victorian life that would be unclear to a modern reader. 

Not only would this be a useful feature for readers, it would spur book sales If for instance a popular author were to annotate his favorite books, people would buy those books from iBooks to experience that annotated version.