UPDATE
This question was originally asked at a time when there was no support for programmatic file creation (via url for example). That has changed, see: http://code.google.com/appengine/docs/java/blobstore/overview.html#Writing_Files_to_the_Blobstore
I'm accessing a couple different APIs to fetch images. My application is GAE + Python and I want to use the Blobstore to save these images. The GAE Blobstore documentation provides clear examples of how to save images to Blobstore via a form, but not directly from an url.
I want to know how to save http://api.website.com/images/foo.jpg to the Blobstore.