It could be a big print run, a small one, a single book. Your biography could just as easily have no print form and be purely an e-book. Traditionally the concept of an autobiography or a biography has almost always included the printed page, often very expensive to produce in small numbers. Producing a downloadable PDF e-book is a very cost effective way of creating a professional text that can be sent to large numbers of people via email.
One new medium of publication is Joomag. They allow you to put music, photos and text together in an interactive presentation format. The advantages are most pronounced when there are limited resources and there are a lot of poignant audios.