You have any interest in implementing this Dean?
I've got a lot of things already lined up to work on for a good while and this still seems kind of a strange scenario to me. A user uploads images to some other ftp server and then copies links into the module. It just seems a lot more likely they would ftp the images to some directory in the mojoportal site. Also image files can be very large if they come right out of a camera in high quality so you really need to make sure the one displayed is a reasonable web size.
My dream for a gallery would be to use F-Spot to manage my whole collection. There is already a google sharp
library in mono that could be used and someone also implemented picassa support in F-Spot
to export images to picassa web so a picassa module would be a solution I could get excited about.