As noted - Lexus does not have an update nor do Palm or Verizon. I did find a fix tho!!
My car (2006 GS) sees my phone (Treo 700wx) OK and seems to work for a while, then stops. If I stop the car and restart the connection the comes back. Through trial and error I found out (I think) that if I leave the phone on (change power settings so it does not turn off) the bluetooth connection stays.
Chris