The dealership told me today the diesel won't be installed in the X3 in 2012 but they told me the same thing about the n20 too... who knows? Maybe BMWNA keeps the dealership's in the dark until the last minute too. 
Rumours are that a diesel engine will also find its way into the X3 in 2012.
It sounds like it might be the 30d but I'm hoping for the 35d... the diesel will have the performance of the 35i and better fuel economy than the 28i/n20.
Interesting, thanks.
I usually know things before the BMW dealer. But they will follow up for me quickly and usually confirm for me as soon as they can. Sometimes they do not get the confirmation until weeks later.
They've known me for two years now. I have known things before the general manager, etc. They like to tease me because my track record has been, well, 100% to date.

It's all because of the info on the forums, from insiders, etc. I noticed you're active on the X3 forum now. You will have the same track record as me.
I think it's because insiders drop hints, leak info before. And unlike us potential buyers with keen interest in 1 or 2 models, they have all the models to know about. But my dealership has a really good attitude I find... They try to confirm for me as soon as they're able to.