Here's what came in the box:
The bluetooth module:

The wiring harness:

The wired mic:

It also came with a green "call" sticker, and a red "end-call" sticker. I don't think I'll be putting these on my steering wheel, but if anyone has an extra set of the the 2009 steering wheel controls with the phone call symbols I'd be interested in buying

.
The install was very simple. I didn't take pictures, but I used
this pdf guide for reference, and it was very helpful I think it was created by lorennerol, or at least he
posted it. The dash wasn't too difficult and I didn't even manage to break anything. Getting the various wires disconnected without a lot of slack was the most difficult part.
After the dash dis-assembly it was as simple as plugging the factory wires into the splice harness, plugging the connectors on the harness into the back of the stereo, and then plugging the harness and mic into the bluetooth module. There was just enough room behind the brace panel to stuff the module and excess wiring.

(this is from a Solstice, but the Sky looks the same)
I ran the mic wire out the left side behind the center console and clipped the mic on the plastic trim panel on the transmission tunnel. It sits about mid-thigh. It picked up my voice well on the few test calls I made, and worked well for voice recognition. I figured having it down lower might make it function acceptably with the top down, but haven't tested it yet.
The interface works through the steering wheel controls whether the radio is on or off. If the radio is on/playing a cd it mutes that audio and switches to the bluetooth audio. A long press of the mute button still brings up the OnStar call dialog, so I figure you still retain full OnStar functionality. I'm not subscribing to OnStar so I couldn't do any further testing.
The bonus of this module is it also supports A2DP audio streaming and works with the steering wheel controls as well. Now the big downside to this is that the audio only plays over the front speakers. I imagine that it's a power-out issue from the module (not enough juice to safely power all the speakers). I emailed the company to ask if it would cause issues, but I'm considering splicing the audio out from the module to the low-level rear audio inputs to see if I can get that signal to my amp. I figure since the audio out from the stereo with the Monsoon system is a low power signal to the amp, the module should have enough power to send the low power signal too with out overloading.
I have the wiring diagram for my car, but not the module. Before I put it in I did some tracing with my multi-meter and it seemed that there was a connection between the low-level inputs and the module, but obviously I was missing something because the rear audio no-worky.