I use and love the Jawbone II, I drive over 50k miles a year and in CA handsfree is the law.
Started with the original Jawbone two years ago and bought the II when it got smaller. Never an issue and works great with the Pre. You have to get used to answering the phone with the Jawbone button (not the button/swipe on the phone) or the Pre thinks you want to cancel bluetooth.
Is this normal? I dont know , but I am used to it already...
One great tip to offer: I found a company at a motorcycle tradeshow called BIGEARINC.com that created for me a custom fit earpiece for my Jawbone II. It was about $90, but completely worth it if you wear your Bluetooth device as much as I do. Makes you forget you are wearing it, stays firmly in your ear, and eliminates the need for an earloop.
http://177.bigearinc.com/Products/BE-JBA.aspx