MY '03 it was 90,000 mi. then changed to 60,000 in '04 or '05 and issued a bulletin to dealers to recommend the '03's as well.
The 6 speed starting with the V6 in '06 was 60,000 mi. as well. The valve bodies in the 6 speed have had some issues so more frequent changing is a good idea.
Some 5 speeds have had valve body issues too but fortunately in both 5 an and 6 speed they are relatively cheap to replace.
So bottom line change your fluid every 30,000 mi. It costs a bit more than a synthetic oil change and cheap insurance.
I thought it was every 60k until I was told its recommended to do every 20k, my car only got 50k but feels a bit sluggish, will change it very soon, already did on one of my 9-5's which has 150k and wow what a difference! Car would take couple secs to change gear from R to D. Now it's almost instant, and when you do hard accelerations it's very smooth, and noticed better economy, was getting about 900km on one tank, now get 1058km on one tank, so noticed an improvement on efficiency too.