I'm not aware of anyone using GraalVM for its language interoperability in production. However, it's used by GraalVM languages internally for supporting things like C extensions and FFIs.

So far, there's been a lot of interest in the performance improvements that the Graal compiler provides [1] and GraalVM Native Image [2], the toolchain that allows the compilation of Java apps and Truffle languages into binaries.

But, there's a lot more you can do with GraalVM [3].

[1] http://www.ssw.uni-linz.ac.at/Research/Papers/Stadler14/Stad... [2] https://www.graalvm.org/docs/reference-manual/native-image/ [3] https://www.graalvm.org/docs/why-graal/