This is a quick wrapper around an S3 class by Donovan Schonknecht that will recursively upload your files in a subdirectory to an S3 bucket, applying Cache Control control headers as it goes.
The original intent was to have a quick way to sync images on a development machine with a live S3 bucket that was serving images on a site, without having to use any crappy third-party software. This was spawned out of the need for a simple uploader that actually works. So far it's been great.