I've copied one of Adobe's CS3 icons into a screen grab of the new Finder icons in Leopard and they are remarkably similar. Either Adobe & Apple are sharing designers or they are in close contact to make sure everything looks just right when Leopard is released. Personally I think it is the latter of the two, but maybe the interface improvements in Photoshop CS3 also correspond to some extra interface improvements we don't know about in Leopard. Probably not, but there's nothing wrong with a bit of rumor mongering.
There's only so many ways you can design a folder... Nevertheless, Apple and Adobe have been entwined for years now. There's bound to be some GUI overlap somewhere in there.