I have been corresponding with a military sales representative regarding purchasing a new 335i and have received information which indicates the new iDrive will not be coming to the 3 series sedan until the 2014 model year. Here is the direct quote lifted from my email from my CA. Please excuse any gramatical errors, this is from Germany after all.
"Iíve just received the confirmation again that the NBT hardware will be launched on all F30 US models in July 2013. The worldwide F30 models will have the NBT hardware as of November production, but as the US market has to fulfill the requirement to offer major product changes in conjunction with a new model year, the launch has been postponed to July 2013."