I have an issue as well with uconnect on a 2008 chrysler 300c.
Uconnect triggered "Incoming Call", I pressed the answer button and the call stayed on the handset, tried to move the call to uconnect on the iphone4 handset but it wouldnt transfer.
I hung up the call and tried to dial out, again the iphone kept the voice on the handset.
After a 3rd attempt the phone transferred the call to the car after about 1 minute.
When I parked the car the iphone would not let me select the iphone as an audiosource, I had to go into settings and turn bluetooth off on the handset to get the call back.
Car has just been updated with the latest firmware for uconnect and worked perfectly with the 3gs, even with ios4.
Bizzare, but very dangerous!