Just for the full story (and to confuse matters a bit!), the North American version of the HF puck looks the same as the European SAP cradle, so if you read about SLR type cradle on US forums remember that.
The reason the Euro SAP cradle wont work with iPhone is that the iPhone doesnt support the Bluetooth profile called SAP
The iPhone V2 software and iPhone 3G actually dont download the phonebook into the HF puck ("HFP") at the moment (also BMW and other manafacturers kit as-well). I'm sure Apple will fix their phone software at some point.
The MBU-2000 (follow link above and look at other cradles) is not a MB product but does work with the new iPhone software / iPhone 3G - it is software upgradable (return to base though) and the manafacturer has brought out software for the cradle that works round the iPhone issues.
There is a MB specific iPhone cradle, which does download the phonebook and charges the iPhone. But it doesnt work in cars with D2B audio system (i.e pre mid 2004 build and W163 ML) as you get echo, and doesnt fit in A/B/CLS and possibly some others also - again pictures/details can be found by following the link above and browsing
Richard