you can't use bluetooth at the same time as another application that requires access to web based apps. However, I have an Iplug (3.5mm jack) to my stereo system in my car. so that when I use the navigation it plays through the radio. Really cool. I also use it to listen to sprint tv, such as comedy central's stand up. I couldn't do that before with my fm transmitter.
I ride a motorcycle and I bought the phone because I thought I could get navigation through my bluetooth helmet. I'm very let down that option was not included.