Since the GMAT is a "standardized test" used to objectively compare students there is no reason for GMAC or ETS to differentiate or handicap the examination based on geography. Think about it -- if it were true don't you think it would be cost effective to fly to, say Tonga, to take the test and get a nice vacation rather than spend $3000 on a prep course and private tutoring? Moreover, the GMAT would lose all credibility as an objective metric should the test be handicapped in any way base on geography.
Former Senior Instructor, Manhattan GMAT and VeritasPrep
Vice President, Midtown NYC Investment Bank, Structured Finance IT
MFE, Haas School of Business, UC Berkeley, Class of 2005
MBA, Anderson School of Management, UCLA, Class of 1993