@moonbeamlabs and I hold a workshop about ArangoDB and the Ruby driver Ashikawa, which will hopefully become one of the first DataMapper 2 NoSQL drivers. Currently, we are using the aequitas and virtus components of DataMapper 2.
Slides of the workshop can be found on slideshare:
I also gave a short talk about the possibilities of using MRuby in ArangoDB. In preparation for this talk, Achim did some experiments using JIT compilation of the RiteVM bytecode using LLVM. The results are consistent with result for other byte-compiled languages. You can expect a speed-up of 2 using LLVM. In order to gain larger improvements one needs type inference and optimizations to the method selection. Luckily within a context like ArangoDB one can expects to be dealing a lot with primitives types (floats and strings) and a fixed environment. So it seems plausible that one can eventually get near the performace of V8.