My colleague discovered that you don't have to be in an edit session to annotate a layer. Are the annotations still saved to the database? If, yes: HOW without an edit sesstion??? If no: Where are they stored then?
By "annotate a layer" if you mean creation of annotation, yes you do not need to be in edit session. The easiest way is to label your layer and convert labels to annotations.
If you mean editing the annotations, please note that annotations are stored either in Map doc as annotation groups or in geodatabase as feature classes (either stand alone FC or linked to FC).
In case of annotation groups. annotations are edited directly by updating the text or dragging to a new location as required. In case of annotations feature classes they are edited just like any other feature classes, in Editing session
I hope that answers your question - K Mubarak