With iCloud, when you take a photo on one device, it automatically appears on all your other devices. And with Shared Photo Streams, you can easily choose which of your photos you want to share and who you want to share them with.
Take a photo on an iOS device. Or import a photo from your digital camera to your computer. iCloud automatically pushes a copy of that photo over any available Wi-Fi or Ethernet connection to the Photos app on your iOS devices, iPhoto or Aperture on your Mac, and the Pictures Library on your PC. You can even view your Photo Stream album on your Apple TV. So you can show off your shots to friends and family from whichever device you’re using at the time.
The preceeding explanation of Photo Stream was taken from Apple's website at:
http://www.apple.com/icloud/features/photo-stream.htmlLarry did an Appy Hour on Photo Stream! His Prezi is available at:
http://prezi.com/nh2fd6v2wsgt/photostream/?kw=view-nh2fd6v2wsgt&rc=ref-28463275