I just finished installing my new Pioneer AVIC-X920BT navigation/media receiver. It wasn't nearly as complicated as I was expecting. I got the receiver, trim kit, harness, and antenna adapter off of ebay (Sonic Electronix, $739 shipped). I spent about 30 minutes connecting the wire harnesses together (solder plus heat shrink) a few days ago. It took about 30 minutes to install the unit into my Smart today, including fishing for the screw that fell into the dash 
I decided to bypass the parking brake requirement by connecting the radio's sensor wire and ground wire to the wiring harness's grounding wire. Everything works as you would expect it to. I left the speed pulse wire disconnected (didn't buy a CANbus to speed pulse converter), nor did I do anything with a reverse camera (though that may be coming eventually).
For media, I plan on using the micro-sd slot almost exclusively. For the rare USB or auxiliary jack use, I plan to use a panel mount usb extension (
, $32 shipped) in the glove compartment and will wire the existing aux jack in the glove compartment so that it still works.
I placed the GPS antenna under the dash trim, close to where one of the dash pods would be (if I had them) and it still gets a great signal.
Not really useful for much more than pointing, I do plan to hook up my driving dvr (DealExtreme, $83) to one of the video inputs. I'll be sure to post photos when I get that done.
Everything sounds great with the built-in speakers. I'm not sure now if I'll be changing them.
Edit: Photos added below. Trim kit was a Metra kit.
I decided to bypass the parking brake requirement by connecting the radio's sensor wire and ground wire to the wiring harness's grounding wire. Everything works as you would expect it to. I left the speed pulse wire disconnected (didn't buy a CANbus to speed pulse converter), nor did I do anything with a reverse camera (though that may be coming eventually).
For media, I plan on using the micro-sd slot almost exclusively. For the rare USB or auxiliary jack use, I plan to use a panel mount usb extension (
I placed the GPS antenna under the dash trim, close to where one of the dash pods would be (if I had them) and it still gets a great signal.
Not really useful for much more than pointing, I do plan to hook up my driving dvr (DealExtreme, $83) to one of the video inputs. I'll be sure to post photos when I get that done.
Everything sounds great with the built-in speakers. I'm not sure now if I'll be changing them.
Edit: Photos added below. Trim kit was a Metra kit.