Some units have MirrorLink that displays and controls the entire phone from the actual in-dash Touch Screen itself.
Just look for any stereo that has MirrorLink for iPhone
Most stereos will have the option for steering wheel control. You need to buy unit separately:
http://www.amazon.com/Axxess-ASWC-1-...SQQH5EQ3C4BRTW
The steering wheel control will only control the Source of the radio, the Volume of the Radio, and the seek track for the radio.
Other stereos have iPhone apps, where you can control certain features from your phone using the Stereos interface.
Below are a few examples (Non have built in GPS):
Pioneer SPH-DA210 AppRadio 3 Smartphone receiver with CD/DVD player at Crutchfield.com (Although i'd wait for the AppRadio 4, no word on release date though)
Alpine ICS-X7HD Digital media receiver at Crutchfield.com (Nice head unit but pricey)
JVC KW-V40BT DVD receiver at Crutchfield.com (probably best bang for your buck)
Pioneer AVIC-5000NEX Navigation receiver at Crutchfield.com (This one has Built in GPS and has all the bells in whistles for iPhone controllability, as well as endless of customization, i played with one at the local best buy, awesome unit)