Right now when you do a recursive GET with pegasus-s3, it will create empty folders for zero-byte keys that end with "/". There is no symmetric functionality for a recursive PUT with empty folders. It is not necessary to create "folder keys" for the S3 web client to interpret keys with "/" as folders, but in the case that an empty directory exists, a recursive PUT will not create a key for that folder. I'm not sure if this really matters, but I want to record it so you can decide what to do later.