It's been replaced (on the iPad) with a far more subtle approach. An icon of circling arrows will appear at the top left of the status bar.
The iPad now syncs in the background,yes you can use it while it syncs (though I'm not sure what would happen if you were using an app while it's data got updated. There is no need to warn people that unlocking it will stop the sync, so that text went away.
If you need to cancel a sync from the iPad go to Settings > General > iTunes Wi-Fi Sync and tap Cancel Sync. This seems to work for both cable and wi-fi syncing, btw.
Though I seem to have a bug. The iPad happily stops syncing, but iTunes on the iMac doesn't get the message; nor can I tell it to stop. Strangely I can right click on the iPad and start the sync over. Otherwise I end up having to restart iTunes. It doesn't seem to hurt anything, so just a minor annoyance.