I've been trying to figure out the same thing. It would be good if all your friends can add photos to one stream. Does anyone know if this is possible?
Now you can share just the photos you want, with just the people you choose. Simply select photos from the Photos app, tap the Share button, choose who you want to share your photos with, and they?re on their way. Friends using iCloud on an iOS 6 device or a Mac running Mountain Lion get the photos delivered immediately in the Photos app or iPhoto.