"Syncs every hour"?
 

The sync FAQ says that the iPhone client syncs every hour.

I *think* you mean to say that, when OmniFocus is the currently loaded iPhone app, it will sync if more than an hour has gone by since the last sync.

That's very different, because if my phone is off, or if I'm not using OmniFocus, the iPhone copy won't become current again till I switch back to OF.

If syncing were instant and omnipresent, this would mean the same thing. Since it's not instant, it means I'll be happier if I launch OF before leaving the house, where I have fast Wi-Fi, instead of waiting till I'm down the block, or (worse) underground in the subway.

Right? Or did I misunderstand, and OF can somehow do the yet-impossible background sync by way of MobileMe?

Yes, you're correct.