I noticed this exact same problem when I got my 08 4.8i in Jan and posted this exact same question a few days after picking her up. I took it to the dealership and they said I have the latest software update so they did a transmission software flash so it would readapt to my driving. It still has this problem now after almost 1800 miles! I would love to know how to go about getting this fixed also. I noticed for myself it only happens in D mode when I put it in the manual mode and up and down shift through the transmission shifter the jerkyness is gone.