Thanks for the post. I think you have well expressed our initial frustration. You are right, BMW states very clearly that iDrive cars WITH the CD changer accessory SHOULD play mp3 CD's. Unfortunately, people are saying that it is not working as specified. Please let us know if you have experience otherwise.
This is a particularly vexing problem for me. Mainly, I want to know if this is a software issue or a hardware issue. If it's correctable with a possible future update, then I have hope that they might also give the in-dash CD player mp3 play capability. This has been mentioned by knowledgeable members such as E90Fleet. If it's a hardware deficiency, as Flyboy-SA's dealer recommended solution leads us to believe, then I guess we will just have to wait for BMW to release the "Correct" cd changer.