TiSP. See here for a detailed guide.

Google TiSP (BETA) is a fully functional, end-to-end system that provides in-home wireless access by connecting your commode-based TiSP wireless router to one of thousands of TiSP Access Nodes via fiber-optic cable strung through your local municipal sewage lines.

Not anything like as subtle as Gmail Paper. Aimed at the 5- to 9-year-old male market I’d guess.