It has a motion detector. In theory it can be used to control games by tilting the phone... that kind of thing.
The phone ships with "motion tools", which includes a beat-box thing where you choose an instrument and shake the phone to "play" that instument. There's also a number "game" where you just shake the phone to basically roll dice and that's it.
On the E760 (European GSM A960) and the Korean CDMA variant, one can control many aspects of the handset via motion control, from controling the media player without button pushing, to answering and dialing calls.