Apple website:
"Keeping a complete set of your photos on your Mac is as simple as turning on Photo Stream in iPhoto or Aperture. Every new photo you take appears in a Photo Stream album just as it does on your iPhone, iPad, and iPod touch. But since your Mac has more storage than your iOS device, it automatically imports every picture from your Photo Stream into your photo library so you can edit, delete, and share the ones you want. Want to get the photos youve taken on your point-and-shoot or DSLR camera into your Photo Stream to view on all your other devices? The photos you import to your library from a camera or SD card are automatically uploaded to your Photo Stream. If you have a PC, you can auto-import and upload pictures, too. Just turn on Photo Stream, grab a camera, and start shooting."
"Keeping a complete set of your photos on your Mac is as simple as turning on Photo Stream in iPhoto or Aperture. Every new photo you take appears in a Photo Stream album just as it does on your iPhone, iPad, and iPod touch. But since your Mac has more storage than your iOS device, it automatically imports every picture from your Photo Stream into your photo library so you can edit, delete, and share the ones you want. Want to get the photos youve taken on your point-and-shoot or DSLR camera into your Photo Stream to view on all your other devices? The photos you import to your library from a camera or SD card are automatically uploaded to your Photo Stream. If you have a PC, you can auto-import and upload pictures, too. Just turn on Photo Stream, grab a camera, and start shooting."