It seems the Semantic Web is truly taking off with MIT/Inrupt.com's SOLID effort - where all communication between decentralized machines is via rdf triples. We are about to launch this commercially.
It may alarm you, but I cannot tell if you are joking or not.
Cisco was running Tuple Spaces data stores, in 2001. The queries/unifications were pretty simple, I can't recall their use case. But they were using a system internally and very happy with performance.
I never heard about it again, after a couple of conference papers.
I could imagine that the project died because it was impossible to sell. Semantic Web researchers find nothing odd in the discovery that a networking company has some understanding of applications of graph theory. But convincing upper management, or customers, that they can compete with Google and Oracle at the same time... no.
Tuple space projects were pretty popular commercially.
There was a pretty decent implementation in Java[1] and very scalable distributed implementations.
The problem is that they are stuck in the space between the flexibility and developer friendliness of databases, and the KISS approach of a simple cache.
