The thing to remember is that meter (or stress) exists in prose as well as verse lines (the good ones), so there's no logical way of drawing a distinction there. The thing we lose in prose is a beginning and an end to the rhythmic pattern. It's the difference between a river and an ocean, but the ripples are still there. Stress can still serve its most effective, poetic ends: it adds expressive substance (music) to thought and ideas.

I find this contradiction (poetic stress or meter in prose) to be one of the marvelous features of good prose poetry. We're confronted with a formal paradox, a paradox which, rather than knotting things up in a tight little system, has the capacity to explode the genre entirely.

Prose also functions as a sort of Trojan Horse. Tate said somewhere that a reader encounters prose as an innocuous bit of writing, nothing to be afraid of, a little piece of everyday life. But lo! the reader steps inside and boom, what happens? The linear, often transparent functions of utilitarian prose are completely subverted and instead we find ourselves riding lyrical waves without the comfort provided by the shores of lineation.

Chad makes a good case for lines, though, in his attentive readings of semantic differences--which are also usually a product of where stress lands (i.e. the beginning or end of a line). I would never suggest turning ones back on lineation, anyway. Nonetheless, the contradictory formal nature of prose poetry offers an array of fascinating possibilities. Don't be afraid, step inside and be washed away by the obliterating chaos that is lyric prose!