Here are the universities that Presidential and Vice Presidential nominees of the last nine elections attended. The Democrat is on the left, the Republican on the right. If I counted correctly, these 36 slots were filled by 23 different individuals.
2004: Yale, Boston College(law) v. Yale, Harvard(MBA)
vp: NC St., North Carolina v. Wyoming
2000: Harvard v. Yale, Harvard(MBA)
vp: Yale v. Wyoming
1996: Georgetown, Yale (law) v. Kansas
vp: Harvard vs. Occidental
1992: Georgetown, Yale (law) v. Yale
vp: Harvard vs. DePauw, Indiana (law)
1988: Swarthmore, Harvard (law) v. Yale
vp: Texas v DePauw, Indiana (law)
1984: Minnesota v. Eureka
vp: Fordham (law) v. Yale
1980: Naval Academy v. Eureka
VP: Minnesota v. Yale
1976: Naval Academy v. Michigan, Yale (law)
vp: Minnesota v. Kansas
1972: Northwestern (graduate) v. Duke (law)
vp: Yale vs. Johns Hopkins
Harvard is on a five-election streak (thanks to GW Bush's MBA); Yale has a nine-election streak. Before this, the trends are distorted a bit. For instance, Duke Law is represented in five elections, because Nixon was on the national ticket five times - twice for Veep, thrice for Prez. Other than that, however there is greater diversity in colleges (Goldwater and Truman didn't even degrees) until we go back to Harvard's FDR.
Anyway, John McCain attended the Naval Academy.
Hillary Clinton attended Wellesley and Yale Law.
Barack Obama attended Columbia and Harvard Law.
The Ivy League, including Harvard, Yale, Princeton, Cornell, and Columbia (there are others, but are not represented), are represented in every election, except 1964, going back to 1928. 1924 also appears empty of Ivy Leaguers, but they were represented in every election down to 1900.
Clinton seems to have the advantage of the Yale streak, but Obama has the Harvard streak plus another Ivy League school to his credit. To be safe, McCain will probably get a Yalie as a running mate. Then again, he is a white man, and, while I haven't looked it up, I'm pretty sure white men have quite a lengthy streak in Presidential elections.