The AVR Butterfly is based on the Atmel AVR ATMega169. This mcu has 16K of program space and 1K RAM. That 1K of RAM isn't too bad when you consider that this chip is expected to be programmed in C.
I'm getting pretty good at cutting C for the AVR chips. But, this would prove to be too cumbersome to really do anything "interesting" with the iRobot iCreate (which I refer to as "the turtle"). I could write C code to do some basic tasks, but I'd rather have a means of scripting the turtle. On a bigger mcu (ARM7, etc) I'd just load up Lua or Tcl (or some implementation of Scheme). But, 1K isn't a lot of space for dynamicism.
So, I am going to scour the web for any decent alternative programming languages for the AVR (but not BASIC and what FORTHs I've seen don't do much for me). If I can't find one, I may have to roll my own!