Actually, Rabbits do have a digestive process very simmilar to rumination, see here:
http://www.grisda.org/origins/04102.htm , so the Bible's explaination is perhaps not so wrong after all.
Also I would like to mention that the passage does not say that rabbits are ruminants, only that they "chew the cud" which they do, via refection, not regurgitation.