Yes they are the same, I have my IPod 4th generation cable installed in my computer and had used it with my sister IPod Nano 4th generation, also with my son's IPod Classic
Also I have used four different car power supplies with the IPod 4th generarion and IPod classic. One type was also used with a IPod mini and a IPod 3th generation.
I haven't found any notice of changes in the dock connectors distribution, so most likely from the first dock IPod to the last the power supplies are the same, even the firewire power supplies work with the IPod 3th, 4th and classic(5th), I've tested that.