Fucking brilliant! I'd love to hack on this... are you using app engine? Is it open source? In particular, you know what would make this rock*10^6? facebook/dropbox integration.
I would very much like to have this auto-pull from Dropbox folders; it is something for another weekend. I just posted the source: http://github.com/glenmurphy/dropmocks
Also, to my phone. When I take a picture on my phone, I want it to sync to a dropbox folder.
Also, with facebook. I want each of my picture galleries to sync with a mock (and, optionally, to a dropbox).
Let's say a mock is synced with both dropbox and facebook. Then adding a file to the folder locally on a machine, it should push to mock, then from mock to facebook.