some of the scion units have ipod controllers built in if you get the cable, and the ones that can control a CD changer can use an aftermarket plugin dealio that will control an ipod, and give you an aux-in jack that could be used with a satellite rig and i think also pre-outs for a sub
bluetooth.. yeah probably not going to get that i haven't looked into it in a long time
the real bonus of the scion units to me is the distinct lack of interest from thieves. i put the scion unit in mine after someone broke in and tried to take out the blaupunkt (which was ancient anyway).
if you want to add the aftermarket ipod control thing, money is probably a wash with a full aftermarket HU tho