In oblivion you can have a sword and sheild equipped, and then press a button to cast a spell instantly, no delay. For a moment the sheild disapears as you get a spell out instantly, and then the sheild returns right back to be used.
During the demo Todd equipped a sword and a spell in each hands, and the crowd 'ooed' and 'awed' while he explained how you can use both.
Am I missing something here, or has that already been a feature, and from the looks of things is worse, since you aren't using a sheild when you aren't casting?