Just happened to have my front tires off last weekend and it's a 07 2wd so may help here. Look at one, if you have a dust cap then you probably have the same ones as on the 97-03 where you can change out just the bearings or hub/rotor assembly. If when you check the front wheel, if you immediately see the cotter key and nut for the hub assembly, then you have the sealed unit so you need the whole assembly that includes the sealed bearings.
Called the local dealer just to be sure on saturday, said that mine has the sealed unit so if you have to change anything, it means buying the whole assembly.
If it gets to the point I need to change out the rotor etc, I'm going to look into these:
http://extranet.soleniuminc.com/Cent...&mm=F15SERPU2D
Apparently you get different hubs for the front and it uses a 4x4 rotor, so if you ever need to change out the rotor in the future you don't have to change out the whole thing. I saw this on a forum recently and it looks promising.
Paul