I recently found out that probably half of the Windows Phone 7 users have not updated their phones to Mango yet. Being a techie this baffles me. But for the end user I suppose it could be understandable. The iPhone you always needed iTunes to update your phone and with Windows Phone 7 you need Zune. The difference is when you buy and iPhone you need iTunes to even use the thing at all so users are much more aware that the phone relies on iTunes. I am not sure if you still need iTunes with iOS 5 but historically you have.
Windows Phone 7 Updates
Windows Phone 7 (WP7) has been out for a little over a year and has had 2 updates pushed out. The first update was NoDo and was pushed out almost a year ago. The most recent was pushed out just last fall and was nicknamed Mango. A lot of users probably have no idea how to update because they are not familiar with the Zune software.
Zune is to WP7 as iTunes is to iPhone.