The author already wrote it’s own Ruby implementation (which runs on top of PHP engine). It’s said that every true smalltalker tries to write his own VM for Smalltalk, better than every other (based on this, I’m true smalltalker). Maybe it’s time to say that every rubyist tries to write it’s own Ruby compiler :-)
A natural question is: why java programmers never ever thinks about writing their own Java VM/compiler? What do you thing?