A recent article in Canada's Financial Post Magazine (http://www.financialpost.com/magazine/story.html?id=2629735) questions the value of MBA program rankings, claiming that their influence is shrinking as applicants start to rely more heavily on the schools' own websites. The sheer number of and variation among rankings - different magazines and websites use different methodologies, and rankings are further subdivided by full-time, part-time, Executive MBA, and MBAs by specialty - is causing ratings fatigue among both applicants and employers.
The ranking popularity began in 1988 when BusinessWeek first published its ranking in the popular press...and other major publications began to follow suit. Business school deans are mixed on the value of the rankings, understanding that they have significant public relations value, and yet also realizing that there are ways to emphasize different subjective criteria in order to climb in the rankings, which may have little to do with the quality of education. Various proposals suggesting criteria like alumni happiness levels at various points after graduation, or employers' happiness with hires from the schools are floated, albeit with little chance of being implemented.
The bottom line is, whatever your opinion is of rankings, the most important way to assess whether a program is right for you is not to look at where it lands on various lists, but to do your research thoroughly and determine which program has the best fit...for you.