Wi-Fi Sync is an App that allows wireless syncing over a Wi-Fi network (of course) with iTunes. The catch is that your iDevice has to be jailbroken.
By the devs own admission, in the video, it‚Äôs slower than USB, ‚Äòbut not horrendously slow.‚Äù Wi-Fi Sync is available for $9.99 on Cydia. You also need to download and install the free app. At present it is only available for Mac OS X but a Windows version is promised for this summer.
WiFi Sync free on Cydia
Need to jailbreak your iPhone or iPad read our Jailbreaking Guide.