Apple last week released a new Apple Keyboard, which offers Apple's sleek aluminum look and two extra USB 2.0 ports, but no numeric keypad. The keyboard costs $49 and requires that you be running at least Mac OS X 10.5.6 Leopard.
In the recent past, if you wanted a small aluminum keyboard from Apple, you had to purchase the $79 Bluetooth-based wireless keyboard. It eschews a numeric keypad and suffers from the hassle of dealing with batteries and Bluetooth, though it does eliminate a cable from your life.
The new Apple Keyboard is noteworthy for people buying a new iMac because it's the default option when you shop from Apple. For the moment, though, you can substitute the Apple Keyboard with Numeric Keypad at no extra charge (the default situation is reversed for Mac Pro purchasers). For those buying a Mac mini, both keyboards cost the same. The Apple Wireless Keyboard costs an extra $30.