As arc develops, it might be worthwhile to implement subsets of it in other languages for comparison. Then some of the sample applications can be written across all these alternatives. At some point there might be a few examples or an implementation point where its infeasible (i.e., very painful) to use anything but Arc itself.
Great idea, a port to CL (where I have my best IDE). I want to do a rather intense Arc library, not sure how much cut/paste I will survive. Gonna have to quit the day job...