I did this installation this morning (did not have any issues) and was hopeful it might fix the issue I have had since the 4 upgrade.  Since I have upgraded to iOs4, I am no longer able to listen to my iphone through the usb cable in my 2010 camaro..  It gives me a message that it is not supported, which it previously did, but they now added the “not supported.”  There is no change in the 4.01 update.

iPhone owners say iOS 4.0.1 installation buggy – ZDNet.