I kind of liked this article in the new American Poet, "Poetic Structure and Poetic Form," by Michael Theune. Theune argues that the structure of the "turn" (used most frequently to describe the structural movement of a sonnet between the quatrains and couplet or between the octave and sestet) can be considered a formal device in the context of contemporary poetry. He defines the turn "a significant shift in the poem's rhetorical progress."
Theuen then suggests that one might classify poems based on their types of turns, for example:
1. ironic = poems turning from set-up to punch line
2. emblem = turning from description to meditation
3. concessional = turning from initial concessions to making a positive argument
4. retrospective-prospective = turning from past to present or future
5. dialectical = turning from thesis to antithesis to synthesis [me: isn't this an ode?]
6. descriptive-meditative = turning from a description of a scene to a meditation that arises from the initial description to a re-description of a scene
He doesn't suggest that that list is exhaustive.
I like this taxonomy of the turn, though. When I'm writing, there's definitely a sense that the poem moves until some threshold has been reached or corner turned. I mean, the poem doesn't feel drafted until that happens. But I don't have any idea how anything I write fits into any of the categories in his taxonomy--but perhaps that's because I am quite lazy tonight.
Then there's the contrarian thought: can you write a poem without a turn? Have I written a poem without a turn? It seems like the poem has to settle somehow. I think I've written poems with multiple turns that don't fall into that slaloming motion of his dialectical category--and I keep thinking, isn't that what an ode does?