The plugin should allow images to upload in a wordpress site.
Anonymous or logged users can upload images
Must validate the file type and maximum size
Must Store the image on a different server where the installation of wordpress is.
Add the image as a post pending in the list of posts for wordpress
Generate short url
i'm not a php programer o css fan, but im a asp.net programer,
if i do this in .net... it will take 3 hours... or less if you have the right libraries and knowledge.