from this link: http://code.google.com/appengine/docs/whatisgoogleappengine.html
<http://code.google.com/appengine/docs/whatisgoogleappengine.html>"An application cannot write to the file system. An app can read files, but only files uploaded with the application code. The app must use the App Engine datastore, memcache or other services for all data that persists between requests." Installing an application via web2py implies a writing operation - open(upname, 'wb')
