Rethinking this. I think there are two kinds of realigning presidential elections: Demographic and Ideological.
1932 was actually both.
Demographic: 1952 and 1992.
Ideological: 1980 and 2008.
Geographic : doesn't challenge the ideological alignment, only the bases.
1952 - Republicans have a consistent base in the Great Plains and Mountain States
1972 - Republicans dominant in the South for most elections from now on.
1992 - Democrats have a fixed base in the great lakes, North East and West Coast
Ideological: Definite change in the general ideological fixture of politics.
1932 - Government welfare programs and intervention in the economy becomes a norm.
1980 - Reversal of 1932, with cutbacks to taxation and more free market orientated policies.
Maybe it's too early to say 2008 is ideological, but I feel it probably is. Obamacare, LGBT rights and moderate Keynesian economics.