My recommendation is the Parrot system. I have been using mine since August last year with my iPhone 3GS. Not only does it provide hands free phone connection but also complete control of the playlists on your phone or iPod. I also use it with the iPad to watch movies with the sound coming from all speakers in my Mazda 3. The direct connect provides a LCD for viewing your albums and provide the best digital sound available. In addition I have a window mount for the iPhone that I use the GPS copilot for again this time via Bluetooth the directions are heard through out the speakers in the car. One can play music at the same time which fades when the gps announces turns etc. I have tested this with the new os 4 and it is perfect how ever I have not tested it with the new iPhone as have to wait until July for our release.
It also supports other phones and USB as well however its designed more for the Apple iPhones and iPods. Cost in us I do not know go to parrot.com for details.
I forgot podcasts can be handles using the bluetooth function no problems at all.
A complete system dedicated to in-car calls and music
The Parrot MKi9200 is a Bluetooth hands-free system with a 2.4-inch high-resolution TFT colour screen. A wireless remote control can be positioned on the steering wheel or dashboard and allows the driver to control all the functions of the MKi9200.
In addition to conventional telephony functions - pick up, hang up, dual calls - the Parrot MKi9200 boasts cutting-edge telephony functions: automatic phonebook synchronisation, training-free multi-speaker voice recognition, speech synthesis of the names in the phonebook, contact management (up to 2*000 per phone), call records, and so on.
Its colour screen displays the phonebook, caller ID and photo, phone information and user settings. The menus and phonebook are also audible for easier, more intuitive use.
Listen to your digital music in the car
The Parrot MKi9200 is also gifted for music. Supplied with a specific cable, it is compatible with all music sources, such as iPods, iPhones, USB flash drives, Bluetooth stereo (A2DP) phones, MP3 players and any other analogue players. The Parrot MKi9200 also features an SDHC-compatible SD card reader on the side of the screen.
The MKi9200 displays the full playlist along with the name of the artist, the title and even the corresponding album cover in colour when available on the iPod, iPhone or USB flash drive.
Music is delivered through all the car's speakers, giving the driver and passengers exceptional sound quality and the breathtaking Virtual SuperBass and Sound Spatializer effects.