Among some of the many of the changes we'll see for the 2005 model year (LED lights behind the door handles anyone?) will be the introduction of a new key design. Overall the key takes on the functionality of the current BMW 3 series key with separate buttons for lock/unlock functions as well as a button to open the boot.
According to those who have handled the key it's about the same size but lighter and a bit thinner. It's also not curved like the current key but overall fairly flat.