As others have posted, it seems that the iPhone (both original and 3G models) only officially supports the Hands-Free Profile (HFP) and Headset Profile (HSP) hence the phonebook and other problems.
However, I also had a first generation iPhone and it worked perfectly with my 2007 A6 Allroad ... full access to phonebook, recent calls, missed calls ... the whole nine yards.
I have the same problem as you with the 'new and improved' iPhone 3G. I can pair from the phone to the car and get a very basic functionality (i.e. no phonebook or call register). If I recall correctly, you need to initiate the pairing the other way round ... i.e. starting from the car. When successful the phonebook is copied as part of the initial pairing. I can't get this part to work for me as the iphone is invisible to the Audi even though the iphone says it is 'discoverable'.
Applecare will just give you the standard line about not being able guarantee to support every phone out there.
If the 3G is working with other car makes (BMW and the like ...) then it might be an Audi problem. They seem to have created a workaround for the original iPhone's shortcomings so let's hope the can do it again for the 3G
Audi Guy
PS. The following is a list of profiles supported/not supported that I lifted from another post ...
iPhone Support:
Hands-Free Profile (HFP)
Headset Profile (HSP)
iPhone Does Not Support:
Advanced Audio Distribution Profile (A2DP)
Audio/Video Remote Control Profile (AVRCP)
Basic Imaging Profile (BIP)
Basic Printing Profile (BPP)
Cordless Telephony Profile (CTP)
Device ID Profile (DID)
Dial-up Networking Profile (DUN)
Fax Profile (FAX)
File Transfer Profile (FTP)
General Audio/Video Distribution Profile (GAVDP)
Generic Access Profile (GAP)
Generic Object Exchange Profile (GOEP)
Human Interface Device Profile (HID)
Intercom Profile (ICP)
Object Push Profile (OPP)
Personal Area Networking Profile (PAN)
Phone Book Access Profile (PBAP)
Serial Port Profile (SPP)
Service Discovery Application Profile (SDAP)
SIM Access Profile (SAP,SIM)
Synchronisation Profile (synch)
Video Distribution Profile (vdp)
Wireless Application Protocol Bearer (WAPB)