http://dendritics.com/scales/white-rabbits.asp discusses the matter at some length (including debate over whether "rabbit rabbit" or "white rabbit, white rabbit" is proper).

Acknowledging that wikipedia is not considered a "reputable" source by many, http://en.wikipedia.org/wiki/Rabbit_rabbit has some info about it.

And, just because last week Google simply did not *have* an article (I had it in front of me; student said he'd gotten it online, so search terms should have gotten me there... which they *did* on Alta Vista)... which got me to an album title of that name ("rabbit rabbit") by the Hattifatteners. Maybe we should say "hattifatteners, hattifatteners" instead; it has a good ring!

Okay, now I really really will be productive...