Over the Christmas period Amazon announced.
Today we’re excited to announce Object Expiration, a new feature to help you efficiently manage data stored in Amazon S3. Object Expiration enables you to schedule the removal of objects after a defined time period.
This is very cool. Chron jobs are always problematic, it is much better to let the storage system take care of this. You can read more in the Object Expiration press release.
Dr James Bayley 
Object Expiration is a really cool feature, it works well if you need to delete the bucket that contains millions of files. A great way to save the time and bandwidth.
Here is how to configure Amazon S3 Object Expiration using S3 Browser Freeware:
http://s3browser.com/amazon-s3-object-expiration.php