We'll wait for the returns cross-section, but one has to hazard that Santorum was the knife that the GOP "establishment" used to cut Gringich's appeal to the heartland Christianists, backed by huge PAC spending on ads.
If true, that means that Santorum, who never had much polled support in Iowa until recent days, garnered nothing more than a rejection vote, a safe-harbor "value vote", a power-pastor oblation vote.
That's just fine with those pulling the GOP's purse strings, as they get to keep up the illusion of a Reagan coalition that "works", rather than one that is a dangerous trinity for any polity.