Is it possible for my HTC Desire to interupt my iPod when I receive a call? I frequently miss incoming telephone calls because I am listening to my iPod Touch and I don't feel it vibrate.

Does anyone know if it's possible for my HTC Desire to somehow notify me of the call via my headphones?

I've seen bluetooth connection devices that purport to do this (such as the GEAR4 BluEye), but they are several years old now.

However given that this kind of hardware exists, and that the Desire and the iPod Touch have Bluetooth built-in, I wondered if there was an app or setting that would enable the phone and iPod to work together in this way?
I've found something for you, although it may not treat your iPod the right way.  The only way to find out is for you to give it a shot.  Luckily the developer of this app offers a version that's a five day free trial.

Super BT Mono

If you're running stock Android 2.2 try this.
If you're running CyanogenMod try this.

I'd follow the dev's instructions on how to get this up and running, and just treat your iPod like the BT headset with which this app is meant to interface.  It doesn't say so on the app page in the Market, but on some forum thread (of which I've unfortunately lost track, dammit) someone mentioned that it will send notification tones and ringtones to the BT device.