I think the one to get is the USASpec PA-11 Vette. I saw a few threads about that and the STS. Interfaces with the factory XM radio interface. So, you tune to the XM channel and then control the playlist, title and track, etc from the radio. It comes with an updated cable for the iPod Touch and iPhone 3G, 3S charging. The only shortcoming is that you cannot route sound through the speakers for inbound phone calls. So, for that, I picked up a bluetooth interface to RCA to plug into the iPod interface adapter. Now, inbound calls are routed over the car radio. It supports full control (only from radio) and hybrid (some from radio and from iPhone - what I use) which is selectable at any time from the radio. Pretty slick.
Here is a link to that product (a vendor).
http://www.soundsgreat-stereo.com/in...hk=1&Itemid=26
Now, optionally, just pick up an A2DP bluetooth device only and route that to the radio assuming you have a stereo input anywhere. The downside on that approach is that the only control is on the iPhone directly. Not my preference.
And, as a clean up item, you could consider the Kuda USA dock kits that match your interior.
http://www.kudausa.com
All food for thought.
For cradles, consider the ProClipUSA items.
http://www.proclipusa.com