John Sosoka recently gave an interview with Robot Central where he told the them that the Pawn scripting engine was being used for Pleo. Pawn is a scripting language engine that allows embedded systems developers to create custom scripting languages for their customers. This saves their customers from the huge learning curve of having to master the entire platform code base and libraries, just to add some custom functionality like new animations and behaviors in the case of Pleo. Of course there are a few hackers that who would love to do just that, but this opens up Pleo tweaking to a much wider audience. Note, there is no point in "learning Pawn" now since Ugobe needs to create the command set and object methods first. Pawn by itself has only a handful of primitives that are common between implementations; the rest is completely dependent on each host platform and the command set provided by the manufacturer. To learn more about the Pleo Developer kit, you can watch this video on Pleo World, Ugobe's official user site.