The "Ruby" label for this article is rather misleading. It doesn't talk at all about implementation, rather just calling into a library, which is written primarily in C anyway.
Nice article, but Ruby wouldn't have been my language of choice for illustrating HPC concepts.
Why ever not? If you're writing an application in Ruby, you're going to need the fastest algorithms on the block to make up for the interpreter's less than optimal performance. I would think that Ruby (and other dynamic script languages) need this type of technique more than just about any other environment.