fstedie came up with a nice hack for adding internal Bluetooth audio support to your iPod:
1st Ever Bluetooth-Enabled iPod!
If you're like me, you've often asked yourself why Apple has not added native Bluetooth capability to their iPod line up. Even the iPhone only supports mono Bluetooth!
Sure, there are numerous adapters that plug into the iPod's dock connector to give you wireless music, but they are clunky, they come off easily, can't use them with your case and you have to charge them separately!
So, here is my way to add "native" internal Bluetooth support to your 4G iPod. The same method may be used with other iPod versions, I leave that up to you.
The hack essentially involves disassembling a small Bluetooth audio adapter and wiring it directly to the iPod mainboard. Audio input is tapped from the headphone jack and draws power directly from the iPod's battery, giving you a completely wireless and dongle-free audio device.
Check out the picture above, though, and you'll also notice fstedie has replaced the iPod hard disk with a CF card. He has an instructable for that, too. I mentioned Mark Hoekstra's hack to create an iPod-to-CF adapter last year, and it looks like these are now more readily available and can be ordered online. Pretty cool little iPod hacks, I must say.
Add Internal Bluetooth Capability To Your iPod - Link
Convert your 4th Gen iPod to use Flash Memory - Link
iPod CF and SD Card Capability - Link
http://www.hackszine.com/blog/archive/2008/01/add_bluetooth_to_your_ipod.html