One can "graduate" from the Arduino
software platform and start
programming the microcontroller directly, or one can use the Arduino
software platform on a scratch-built board, just as easily. Basically
someone can "graduate" into more advanced hardware OR more advanced
software whenever they feel comfortable, and do the other later.
I have a little Duemilanove here. I'm used to 'bare metal' PIC18 coding.
Since you probably know: what's the quickest route to that on the
Arduino, given that my host is OS X/PPC... I was a little disturbed by
the "just press play" IDE.
--Toby
-Dave