This is not really web2py related question. You can use either the GAE Bulk Loader: http://code.google.com/appengine/docs/python/tools/uploadingdata.html or the remote API directly: http://stackoverflow.com/questions/774265/how-do-i-bulkupload-image-blobs-in-google-app-engine
Alternatively you may decide to store just the paths to images which you upload to GAE as static data.
