iPhoto is gentler
At any rate, for better or for worse, once I walked back inside the Wi-Fi bubble, my lovely picture of Pittsburgh's grey skies -- as well as a random iPhone screenshot -- were in my Photo Stream. I fired up my newly upgraded iPhoto, and, once I clicked "Photo Stream" in the left-hand menu bar, there they were.
See those little radiating semicircles at the bottom left? That's how you know you're looking at images in the Photo Stream -- I guess they're meant to represent, like, Wi-Fi or something. And here's another something that struck me as counterintuitive. You can't do any of the things to these photos that you're used to doing with images in iPhoto -- can't share them, can't edit them, can't even drag them to a folder. And, as noted, you certainly can't delete them. So, what's the point, exactly?
But fear not! While you were busy looking in wonder at that Photo Stream folder, the images have also been silently stored in your Photos library. Dip into that and you'll see the same images, without the little Wi-Fi logo, which you can edit and sort to your heart's content.
This is all a little unintuitive. If you try to edit or move any image in your Photo Stream, you get a pop-up window inviting you to do whatever you're trying to do to the version of the image in your Photo Library instead. It makes sense when you think about it -- or at least it makes sense when I think about it -- but I'm not sure how hard it will be for people to get their head around how it works if they don't think about cloud storage interfaces for a living.
iPhoto can also add images to your Photo Stream, but you have more fine-grained control than you do on the iPhone. While iPhoto by default will upload images you import automatically, you can set your preferences so that it holds off from doing so. (You can stop it from automatically adding the photos to your library too.)