Is it safe to use a device or disconnect it while syncing in iOS 5? Prior to iOS 5, iOS devices that were in the process of syncing with iTunes turned on their displays, locked the screen, presented a prominent warning that a sync was in progress, and offered an unlock slider to cancel the sync:

 

In iOS 5, all this is gone and there is simply a tiny sync indicator in the status bar (the screen remains off too):



Does this dramatic user interface change correspond to a major change in functionality? Is it safe to use an iOS 5 device while a sync is in progress; is it now safe to interrupt the sync?
If you mean 'can I unplug my cable', then sure. It'll kill the process for that specific sync and you'll pick it back up next time. If you want to use your phone whilst syncing then you certainly can.

If you've gone wifi sync it'll just continue until either the network connection doesn't work, or the machine is stopped, or the sync finishes.