The latest Arduino design is available and I’ve still got this box full of the previous revision – the Diecimila.
But my loss is your gain… you can now get an Arduino for $30! And for a limited time, you can even get a preprogrammed upgrade chip (with 2x memory & 2x storage) to go along with it for $5 more.

(In case you are wondering the difference between the Diecimila & the newer Duemilanove, the newer version automatically switches between USB and DC power where as the older version has a jumper to switch between the two. The microcontroller is the same, the pinout and shape is the same, etc.)