Looks like testable in certain degree on corpus callosotomy patients. Besides that, on the positive side, Piracetam is known to improve cognitive performance in schizophrenia. It also helps in autism. One of the hypothetical explanations of its beneficial effects on brain are its effects on corpus callosum.

I didn't find anything useful about surgical removal of callosum. There is one paper that looks like summary of sympthoms if you have full access - "Corpus callosotomy in children and the disconnection syndromes: a review". Its definitely not the same as if it never developed, however, there must be some overlap of symptoms of the 2 phenomena, given the function of CC in the brain. About Piracetam - yes, it thought that it influences corpus. You can see more info here: http://agingcorpus.wordpress.com/2006/10/10/piracetam/