My setup: iPod Touch 4th Generation - Jailbroken, using BTStack, Kensington Acoustically Amplified GPS Cradle with Friction Mount and a TomTom Bluetooth GPS Receiver for USA and Canada.
GPS App: Motion-X Drive but will probably switch to something with stored maps.
Pros: This receiver uses the SiRF Star III chip. That's not in the specifications but it should be. Picks up six satellites while sitting in my house and picked up eight while on the road. Low battery consumption and automatically turns itself off if not connected for more than 10 minutes. My iPod touch or should I say BTStack (Ahem!) connected effortlessly to the receiver and transmitted the co-ordinates to Motion-X Drive.
Cons: What are all these cables for?! Clearly, this GPS was built in the era of non-standard chargers. Wake up Tom Tom, 2011 is here! If not micro-USB, atleast a mini-USB charger please? And a nokia cable, Palm Treo cable, iPAQ cable? iPAQ cable?? Why? Are those even sold? Anyways, that means I have to get a separate car charger cable for my iPod and pull that out every time the GPS runs out of juice. Ah well, its all about compromise, isn't it?