iPhone 3G: Car Charger + line out + use for calls?

[MBHockey]

I'm wondering if such an accessory for the iPhone 3G exists. I have an auxiliary input in my car stereo and would like to find a charger that will plug into the cigarette charger that also provides line-out so i can connect my iPhone to the auxiliary port and I'd also like to be able to make calls from the phone (so that my voice carries through the iPhone microphone and I hear the other person on my car speakers).

This has the charger and the line-out: http://www.griffintechnology.com/products/autopilot

But i'm not sure if it lets you carry on a conversation the way I'd like.

This is also another candidate: http://www.amazon.com/gp/product/B0011UK2HE/ref=cm_sp_item

But i'm not sure if this is line-out or just regular headphone output. The problem with it being regular headphone out, i think, is that it'll disable the iPhone microphone because it is expecting you to have the iPhone earbuds with the built-in microphone. This is why I want line-out...maybe it won't cut off the iPhone mic?

Thanks for your help.

[warmpabst]

i can tell you the autopilot won't do that. its a great charger in my opinion, but i don't think the iphone works that way. when plugged into the ldock connector for audio line-out, calls are turned over to the speakerphone, not the connected car speakers. from what i've heard the iphone was designed this way intentionally.

[MBHockey]

Yeah, I picked up the Kensington LiquidAUX + the Plantronics 925 headset...so it's all working nicely now.