There is still some question on whether or not the 5th gen iPod nano has the Nike+ receiver built into the device. Mine arrives today so I'll be able to update this thread.
From my readings though, it looks like you still need to plug the Nike+ receiver into the bottom of the device and link with the sensor. If that's the case, there is no bluetooth/wireless chip within the new nano.
If you read the new Nike+ Apple manual, it makes reference to a heart rate monitor. I want to see if Nike is going to announce this today. I have a heart rate monitor from a Nike Triax C8, maybe I can link them up.