Ezra Klein will be watching more than the vote count:
[N]either the media nor party elites respond to Iowa in an easily predictable fashion. There's no simple convergence around the winner. Sometimes, as with Sen. Tom Harkin's 1992 win in Iowa, no one cares about Iowa whatsoever. In that case, the win didn't count as Harkin was from Iowa. Sometimes, a win in Iowa counts as an impressive victory, but not one with obviously national implications — that's essentially how Mike Huckabee's 2008 win was greeted. Sometimes, a win in Iowa vaults a candidate directly to frontrunner status, as happened to then-Sen. Barack Obama in 2008. Sometimes, it persuades the party to coalesce against a threat, as happened with Pat Robertson's second-place finish in 1988.
It's a weak field, and to some extent things are always like this during the primaries. But it is striking how the evolution in sympathies resembles the narrative arc of a season of an hour-format TV drama or reality show, where writers and producers are deliberately tweaking developments to sustain audience tension. Those wild swings in voter preference are clearly predicated on weak initial attachments to the candidates. But I think they also reflect the news-media industry's increasing competence at performing its core revenue-generating function of holding public attention by creating campaign narratives with frequent twists and turns and shifting audience perspective and empathy.