I'm in your identical situation. Let me know if you come up with any good ideas.
I did go look at Circuit City a case logic product that's a neprene round pocket about half the size of a coke can that clips into and hangs off any a/c vent .
For $5.00 bucks I'm gonna try one. If not to hold the phone it may come in handy for misc but it is big enough for any phone.
I'm mainly interested in finding a ear piece or head set that is easy to pop in and out as a true hands free scenario appears to be a dream.
Brad