I bought the Parrot Bluetooth Cell Phone kit (CK-3100) and the harness to connect to the non-Bose Nissan radio harness. Works like a charm!
First, there is plenty of room by the center console on the passenger side. Remove the side cover and you'll see plenty of room for all the Bluetooth boxes. Installing the kit is as simple as plug-and-play with the exception of routing the microphone and attaching the ground wire.
In routing the microphone, I ran it up the A-pillar and into the overhead map light. There are two slots by the light switch that the factory microphone installs behind. I use the same area to keep the microphone hidden.
The display, I just squeezed between the center vent cover and the top of the radio, and used velcro (that comes with the Parrot kit) to mount to the dash. Nice, clean install.
How does it work? Much better than the factory Mercedes kit I had in my C230! Very clear sound and the people I call can barely tell that I'm talking on a hands free phone. Highly recommended modification for those who didn't get the Technology or Connection package. Total cost was just under $200 and my own labor.