I worried through most of last application season that my grades were far too low for admission to graduate school. A disastrous freshman year at college brought down my overall GPA to about a B-. That's fuhgeddaboutit-bad for aspiring academics. The anxiety was compounded by my having been out of school for over fifteen years. Just what were the chances that admissions committees would believe I could come back to school and do grad-level work after such a drawn-out absence ? Would MFA programs be willing to take a chance on someone whose grades did not show absolute freakin' academic brilliance and promise of unqualified success in graduate school?
Fortunately, the answer was yes--though not every program I looked into at the start could have looked past the GPA issues, had I ended up applying. At some schools, applicants must pass through the hoops of the MFA program AND those of the graduate school. Graduate schools at many programs require a minimum GPA. The Iowa Writers' Workshop website states that its Graduate College requires a 3.0 GPA for admission, for example. Other programs, such as Cornell's, do not state a minimum GPA requirement at all. Obviously, it would be to anyone's advantage to apply to programs where a certain GPA will not disqualify them immediately.
Other than that, my advice is to stop worrying about the GPA. If it is truly shabby, perhaps address it in a few sentences in your Statement of Purpose--do this briefly, turn it into a positive, and move on to explain what it is you hope to gain as a writer by coming to the particular MFA program. But really, MFA applicants, don't worry so much about that GPA. Put your best effort into dazzling the admissions committee with a strong writing sample.