It’s a little strange that PodShirt is releasing a t-shirt for the iPod shuffle, given that Apple has more or less given up on the display-less music player. The design is certainly interesting, however, because the iPod shuffle fits right into the “i” on the front of the iShirt.
The official product page explicitly says in big bold letters that the iShirt “can only be used with the iPod shuffle. Any other model of iPod will not work and may be damaged.” This is due in part to the fact that the audio player is held in place with a magnet, and because the shuffle makes use of solid-state flash-based memory, it will not be affected by the magnetic field, though hard-drive based players could be irreversibly messed up. For the same reason, the iShirt is not pacemaker-friendly.
Either way, the whole point is that the shuffle fits right into the “i” on the shirt, so any other player would look goofy. Because you’d look perfectly normal wearing this shirt otherwise, right? If you still want one, the iShirt is $28.99.