Thanks Anu. Until you prompted me to look it up, I'd always thought the English version of the word - 'behove' (rhyming with 'grove' and 'stove')- was 'correct' and the American version - 'behoove' - was a corruption. It turns out that 'behoove' is the historical form and 'behove' is a version derived from reading the word in books and mispronouncing it.
Incidentally, can anyone think of another transitive verb that is only ever used with the subject 'it'?