That's not true actually. Your photos are stored in the cloud. You just can't access them from the cloud because the purpose is to circumvent the cloud experience. If you are taking photos that you do not want to share on photostream, then just TURN OFF photostream on that device until you are finished. That is the simplest "workaround". I'd like to clarify one issue here though. Who else can see your photostream? Are you sharing an account? If so, why? They are free. Everyone should have their own account on their own devices. If you are letting your kid play on your ipad, then you should turn off photostream if you don't want him to see his gifts. Just like in the "old days" when you had to hide the gifts from kids in the house leading up to christmas. This all goes back to my first point of you are trying to get functionality out of photo stream that it was not designed for. They will add it because you are all clamoring for it, but i just don't see the point. You are missing the concept (or think it's irrelevant) that while google offers a place to store photos "in the cloud", Apple wants you to store photos on your devices. NOT IN THE CLOUD. You use the photostream to see your last 30 days of photos and you save whichever ones you want on your device. They set it at 30 days, so you have 30 days to save the photo on one or more or all devices. Photostream is NOT your storage. That's why it doesn't cost any money to store your photos. It does however, BACK Up your photo roll so you can restore your actual camera roll (not photostream) using icloud.
1. iCloud is backing up your photos and you can redownload them at any time.
2. Photostream is simply showing your photos on all of your devices for saving at a later date.
3. If you want to store and view select photos in the cloud, then use a locker service. I have a dropbox app ON my iphone and my ipad and my mac.
4. It is called a "STREAM" because it continually streams photos across all your devices for saving later. These are NOT your photos. If you do not save them on a device after 30 days, you will lose that photo for good.