With iCloud enabled, you can store your data such as mail, contacts, calendar, iTunes music, movie, books and apps on iCloud, bypassing the need to use iTunes on your Mac/PC to sync to your iOS devices. There are however contents on your Mac that you still need to sync to your iDevices, such as your movie, music, PDFs collection. iTunes 10.5 together with iOS 5 make it easy with wireless sync over Wi-Fi without the need of a USB cable.
To enable wireless sync, connect your iDevice using USB cable to the Mac. Under iTunes, on the “Summary” page for your iDevice, tick the option “Sync with this iPhone over Wi-Fi”.
You can now unplug your USB cable. Then click the Sync on iTunes to start data sync wirelessly.
You can also initiate the sync directly from your iDevice. From the Settings app, navigate to General > iTunes Wi-Fi Sync. Tap the “Sync Now” button to start wireless sync.