Borrowing ideas from smalltalk-80 Evan Phoenix (of EngineYard) has created a new Ruby VM. The VM is written in C with Ruby like syntax. Language known as Garnet (formerly known as Cuby). Most parts of VM are written in Ruby itself except GC , Core VM (opcodes) and Primitives which are written in Garnet.
The link to InfoQ article is:
Also look at Ruby VM performance shootout here: