Not exactly a mount with a charger included, but at
www.proclipusa.com they have mounts which are sold in 2 parts; vehicle mounts and device holders. Right now they only have device holders for the first iphone (not 3g) that you can secure a charging cable to so that when you slide the phone in the cradle it starts to charge.
They have different cradles for different cables (not all have the same size end)
This one has a charger cable included, but if you already have a car charger any of the others will do.
I bought one which wasn't quite right for the cable I had (oops) but I was able to use a knife to cut the area where the cable goes into the cradle (not the cable) enough to make the cable fit.
I am very happy with it, the iphone slides in easily and connects right with the charger. The mount also swivles allowing me to put the phone in landscape mode should the need arise.
If you do go with them, just make sure to buy a vehicle mount also, it is a 2 part system so the device mount is almost useless by itself.
Almost forgot to add, I'm sure they will have a 3g version available soon.