Read the press release about the upcoming X6!!
The V8 option will be a 4.4 liter twin-turbo V8 which is estimated to have 400 hp and 450 lb/ft of torque for the X6. BMW states it should make the X6 go from 0-60 mph in about 5.3 seconds.
Since the 2008 X5 are already out and they have the 4.8i and 3.0si engines, I am guessing that 2009 X5 hopefully will have both the twin-turbo in-line 6 and twin-turbo V8 and hopefully the bi-turbo 3.0sd diesel engine for the U.S.!
Anyhow, just planning ahead...