Photos are streamed to Amazon's Simple Storage Service and available for browsing in a browser-based viewer application.
Only thumbnails of each photo are sent to preserve bandwidth, but users can request a full-resolution version of any photo using the viewer application and have it delivered by the Raspberry Pi to Amazon S3.
All of the code is open source and the hardware to build Photostreamer costs less than $75 per camera. The server component can be deployed for free on Heroku's cloud and photos can be stored inexpensively on Amazon's Simple Storage Service.
This project is still in heavy development, but you're welcome to check out the code and take it for a spin, offer feedback and file bugs.
Alpha code, with limited documentation, is available on Github. The repository and server are in separate repos, both of which contain up-to-date deployment instructions.
We plan to release a fully-functioning beta version by the end of summer 2015.