Saturday, Amazon released a new app with functionality similar to Apple's Photo Stream. The app, called Amazon Cloud Drive Photos (free), automatically backs up your iPhone photos to Amazon's Cloud Drive. You can access your photos via the web as well as share them via Facebook, Twitter, and email. The beauty of this, of course, is that your photos are secure in the cloud even as you take them. Without even having to manually upload them, you can access them via any web browser. Amazon gives you 5GB of free storage in its Cloud Drive, and lets you store up to 2,000 photos. Apple's Photo Stream, which is built into the iPhone, is similar, except that it limits you to 1,000 photos. Another serious limitation is that your photos in Photo Stream expire after 30 days. With Amazon's service, there is no time limit. You can store your photos for as long as you want.