Mass image upload with Storage API and Services API
Still in early dev, but checkout  Storage API Populate:


  Storage API Populate provides a mechanism to move existing files
  within file/images fields into storage. The module requires the
  Storage API module.
  
  For a scenario where you have an existing site, without any Cloud/CDN
  support for assets and would like to use Storage API to manage the
  storage and serving of files.