pbreit might be right - you would still end up uploading the file to your server, and then saving to s3. (though if your server was ec2 there might be a way to mount an s3 bucket, not sure though).
i also agree on looking at the boto interface: http://code.google.com/p/boto/ i'm using an older version of the library (just cause i have been too lazy to disturb running code) quite successfully. cfh
