Not really an Arduino option that I know of. The official languages are "spin" and assembly. Looking again at parallax's site, it looks like they also support C and C++, so perhaps there is an Arduino IDE plugin for it now. I've used one a few years back for a dual channel sine wave generator. The chip itself is capable of directly driving a VGA display using just a few passives, and there are all sorts of interesting ideas you can do when you have 8 cores to throw around.
Here's my first motherboard submission to the gadgetbox project: GadgetBox-Propeller. This uses the Propeller CPU which is a custom 8-core CPU designed by Parallax. All of the GPIO pins are the same, so this was fairly easy to lay out. CPU product page Known things to do at this point: Add GPIO pin labels Validate serial programming eCog graphics