They started using a lighter finish so it feels as though the body is allowed to resonate more than the previous years, it doesn't feel like any sound or vibrations traveling through it are absorbed by the overly thick poly finish of previous years. They updated the bridge with the hi-mass bridge which is a little bit thicker and more like a Baddass bridge, seems to help with punch and sustain. They did away with the s1 switch which was problematic and except for on jazz basses nobody liked it. Also the neck, they used lighter tuners, kept the nice smooth, satin finish on the back of the neck, but gave it a tint so it didn't look so anemic. They also gave the front of the headstock a nice glossy finish (that's really just for appearance but it does look nice!) Also the rosewood fretboards I think are finished a little bit, kind of like on rickenbackers, so they're really smooth, and they paid more attention to the fret ends, I think they're rolled fret ends like they had been doing on the American deluxe series necks before 08.
There really are a lot of differences about the 08 and onward American standards. I had really moved away from Fenders for a while before that because I didn't like anything about the American standards of the previous years, and when I played my 08 P bass, first one that was shipped to the raleigh guitar center, I fell in love instantly, charged it to my credit card without thinking twice, and even though it put me in some debt that took me a little bit to work off cause I had no spare money at the time, I don't regret it at all. It's my favorite bass.