Why can't other people share photos on our shared photo stream?

[Pagemakers]

The answer is simple. Add a new option when creating the photo stream: "Allow others to add photos - Y/N"

 

[dotme]

I believe that (and hope) in future updates this will be possible. If you don't want people adding photos to your shared stream just don't give them the permission. Probably when they implement this, you will be able to choose if someone can only view or add new photos. Another 'feature' that they can make is only download a small version (thumbnail) of the photo, and then if you want the full one you choose to download it or not...

This would be ideal. Like sharing a calendar. You could set each user to read-only or full permissions.