No, there is no Bluetooth in the 2008. If you are really interested in adding this feature you can order the following kit from the link provided which give you a ton of good features along with the ability to use a bluetooth phone (but not the vehicle mic). http://www.coastaletech.com/GMX320.htm
LOL, I read an interview with somebody from Cadillac and the guy claimed that GM wasn't sure their customers wanted Bluetooth. I have to say that the OnStar setup is pretty nice, but having enjoyed Bluetooth in two other cars over the past four or five years, I'd still rather have that.
That Coastal eTech GMX320 (and the other lockpick units like it) will not give you Bluetooth capability. Those devices provide an interface between a separate Bluetooth kit and your factory AV system. On the linked page it says right there, you'll have to buy something like the TellPhone 5000vi... that one in particular is mentioned because it has video output (caller ID, for example) and the GMX320 provides additional video inputs. Altogether it's a pretty expensive package just to get Bluetooth.
Technically you could buy one of the TellPhone units by itself and not buy the GMX320, and you'd have Bluetooth, but then you'd lose the automatic stereo mute and in addition to the TellPhone's own mic (which you have to use in either setup), you'd also have to install the TellPhone's own speakers. But a non-video TellPhone is getting down into the more reasonable price range if you don't want all the other cool stuff the GMX320 does...
What about an alternative Nav (with Rear Cam)/ CD / DVD / MP3 / Radio with built-in Bluetooth (for hand free kit).
Does any body know the best one to fit-in the Tahoe and withmore features and less lose on original featureseffects (like the automatic stereo mute ...)?
I suppose it depends on how much money you want to spend. A brand new head unit that does nav and DVD playback and Bluetooth is going to be quite expensive.
Assuming your truck has steering wheel controls and rear AV, you're going to be gambling a bit when it comes to the little integration modules that various companies sell -- a friend of mine who used to be in the car audio business tells me those things aren't very reliable. Also as far as I've been able to determine, nobody is making an aftermarket head unit with any form of OnStar support, if that matters to you.
In my opinion the best alternative is to pick up one of those GMX320's and a separate Bluetooth product. The Coastal e-Tech folks spoke very highly of the TellPhone products when I asked similar questions, but the GMX320 will work with many other aftermarket Bluetooth systems -- it's just AV inputs, basically.