Logo Interpreter in Javascript

Others have done it better, but I thought I'd take a stab at a Logo interpreter in Javascript. So here it is - warning, doesn't work in Internet Explorer (yet).

The TODO list is pretty large. Right now it uses the "canvas" element so it only works in Firefox, Safari and Opera (i.e. not I.E.). I plan to make it optionally use VML (in IE), SVG or canvas.