Occasionally, you might wonder. What went through their minds when they implemented Photo-stream? The concept is plain and simple, you reckon. You enable Photostream on all your iOS 5 devices and your Macs (iPhoto and Aperture). So far so good. You shoot a picture on any iOS device and Bob's your uncle. Your Adams Yosemite look alike marvel finds its way to the cloud and then back to your other devices! How cool is this? A blow-away, to quote Forstall.
In each of the iOS devices and on the Macs (iPhoto and Aperture) storage space is reserved under the label "Photo-stream". Your Photographs shot on your iOS devices are placed in there and get synchronized among each other, up to iCloud and down to all the rest...
That's pretty neat. Suppose you are working on your big ass iMac, and you want to embed a shot of an object close to you into the document you're working on. You shoot one with your iPhone or iPod Touch latest Gen, and off it flies to the cloud and back it crawls into your iPhoto or Aperture Photo-stream. You could have alternatively transferred the same picture to your Mac by attaching the iPhone to the USB, but it takes much longer this way. So, all in all, Photo-stream can't be that bad as a new function in iOS 5. Not?
There's another issue too. Don't know about you folks, but I am one of those, who when I start shooting pictures, I may end-up with a few hundred shots in a matter of hours. I wouldn't like to flood my iPhone's memory with junk shots, really! Certainly, I can switch off Photo-Stream on the iPhone to avoid getting those in my local stream and in iCloud. Fine, but this is no good. First, I lose all my previous stream pics (that's no big deal since they are normally stored in the roll too), but, second, once I turn on Photo-stream again, I open up my iPhones storage pockets to the contents of the stream in iCloud, and all those puppies fly back in iPhone's stream before I can spell 'Paramaribo'. In other words, back to square one. Stuck again. It's kinda like these pictures are really after you, haunting you... You just can't get rid of them buggers. Why couldn't Apple implement a plain simple "Delete" function yielding simultaneous "Deletes" in the remaining Photo-stream containers? Simple question, innit? Call Forstall!
The only 'clumsy' remedy I found is the following. It involves disabling Photostreams in iCloud and in all iOS devices and Macs. When you do that, all your Photo-Stream pictures vanish to nothingness. Of course, make sure you store those that you want safely somewhere before you kill everything. That's pretty easy, because typically your stream shots also get into your iPhoto's or Aperture's libraries. In there they become mortal again, destructible, deletable!
After this kinda housekeeping gets done, you launch photo streaming again in all your devices, Macs and your iCloud.
You might wonder what should a recommended sequence for shutting down and starting up be. I'd tend to believe that when you shut down Photo-stream, you first start the process in the iCloud (click on your account name, up right, and then select 'Advanced'). You then shut down the streams one by one on your other devices and your Macs. All pictures in those stream storage spaces are automatically deleted and stream containers disappear altogether.
When you restart the stream function though, you work in the opposite sense. You start with the Macs and iOS devices, and then you finally enable your iCloud stream service. The iCloud service is the space where everything gets synchronized from. It's like a traffic policeman directing vehicles on crossroads.
Good luck with all this. It's really simpler than it sounds. No rocket science here. It'd be much simpler though if some bright young lad from inside Apple's iOS engineering troops woke up one morning and sighed, "I'm gonna put a 'delete' button somewhere in the stream, kids"... His Jobness bless him.