Configured my X3 options today. The dealer was aware of iPhone apps but wasn't sure of the option. Scrolling down the list 6NR - Mobile Application Preparation - £130 -- was available. When we chose a pop window came saying option 6NF -- Telephone USB audio interface - £70 -- was needed to proceed. I had already chosen Prof Media package but despite having it I needed to add the 6NF to proceed with having 6NR. So all in all it cost me an extra £200. I wanted the 6NR not for updating my fbk status while driving or tweeting (which adds a whole new meaning to hands free driving) but because of future potential... Due to probs with retro fitting I opted having this now... so may end up £200 well spent or as a donation to BMW coffers
As for iPhone cradle didn't discuss this as currently have a 3GS with contract finishing in July -- most likly to end up with iPhone 5 so will have to see what's available then.