S3

Rsync
"Normally rsync will skip any files that are already the same length and have the same time-stamp."
 * http://www.fredshack.com/docs/rsync.html

Python

 * http://aws.amazon.com/code/134

Ruby
~/bin/s3sync/s3sync/s3sync.rb -r Beginning-iPad-Development bucket:path/path/Apress s3cmd.rb listbuckets  [headers] s3cmd.rb createbucket|deletebucket   [headers] s3cmd.rb list  [:prefix]  [max/page]  [delimiter]  [headers] s3cmd.rb delete  :key  [headers] s3cmd.rb deleteall  [:prefix]  [headers] s3cmd.rb get|put  :key   [headers] s3sync -r Fancy-Book-Title home.lutherbaker.com:/books/Apress
 * http://aws.amazon.com/articles/931
 * http://s3sync.net/wiki
 * http://s3.amazonaws.com/ServEdge_pub/s3sync/README.txt

General

 * http://blog.eberly.org/2006/10/09/how-automate-your-backup-to-amazon-s3-using-s3sync/
 * http://blog.eberly.org/2008/10/27/how-i-automated-my-backups-to-amazon-s3-using-rsync/