We are just finishing building Amazon S3 file upload integration and progress bar plugin for GravityForms. I've read a number of posts asking for these features and we are thinking about making it available for GravityForm users via WordPress.org if there is enough interest.
Anyone interested in giving it a try and sharing their feedback? Please email us at scmediallc@gmail.com
The following features are currently available with the plugin:
-choose a specific S3 bucket or add a new bucket for each file upload field
-specify a folder for the file upload field based on the username of the person submitting the form or a predetermined folder
-ability to turn off local storage of files to the WP-Uploads folder for the upload field when S3 is enabled
