This is in check with what I have been told.

BMW has and can produce the next MY as early as March the previous year.

FYI: BMW released the 2008 e60 Facelift 5 series in 3/07.

Release dates for the X6 look like this.

3/08 for X6 6cly.
7/08 for V8.
??? Hybrid. (I was told that it should be 9/07 for release, but its still up in the air.