The box that this Apple 30-pin to USB Cable - Apple (UK) comes in makes a perfect enclosure for my Duemilanove with room above for a shield and more! Look see ...
... how cool is that?! Shame HMV charged £20 for a cable but that's another story!
£15...for a cable...!?
That's complete BS, and one of the reasons I despise Apple.
Back on topic though, nice reuse of a case :). Looks like it was made for it!
I like OSX (lots) but am indifferent to Apple. Better than both though is ... my Duemilanove in a cute box! Wahoo!
Dude, you got some Apple on your Arduino, bad form. 
Related:
It fits nearly perfectly into an iPod touch case, just need to dremmel out a hole for the USB jack.
It's big enough to hold a 4x20 LCD as well. (That's what I had laying around)
Wish I had a dremmel, would totally make it happen.