Really, I'd lay to rest the possibility of a 3.5L for the NA market at this point. There has been absolutely no hard evidence to suggest that one even exists (and as you can see by the document above, the turbo engine has been in planning for at least three years)...and here we have official press information for the N54. The N54 is clearly real and will clearly be in production in time for the 2007 model year...I myself am almost certain the US will get a version of this engine.
Of course, I could be wrong (even if the currently available evidence supports the above assertion). I'm not in-the-know at BMW, as it is.
I'll tell you this much: if California is the reason that we don't get this engine, I'm going to march over to Washington and put forth a petition "suggesting" that they withdraw from the union.