If you ever wanted to access your Photo Stream files directly on your Mac, this one is for you, the files are located in:

~/Library/Application Support/iLifeAssetManagement/assets/sub/

Just hit command – shift – G in Finder and paste the above path and click Go. You’ll see a list of directories with random hashes, each containing a single file synced from the iCloud. To remove the directories from the view, filter by type Image, and optionally create a Smart Folder.