Ask HN: The current state of Mesh Networking?

I'm a layman with very little knowledge about large scale and wide area mesh networking. I was hoping the good folks here at HN can explain to me what types of mesh networking exists, what problems and what successes they have. Is it possible to use a mesh network as an internet connection? Are there any large scale installations with documentation and stats? Are we forever "roughly 10 years away" from a good solution?

Thank you for your time.