“Don’t you just turn on iCloud syncing, and it all Just Works?”
“Just works” might be the customer experience; but developers must do more to support iCloud (or any new OS technology) than simply flipping a switch. Things can go wrong, and they often do.
Rich gets into a lot more technical detail than most of the other iCloud coverage that's come out recently.
I'm way too familiar with the technical issues described there for comfort.