When the user choses to manually manage music in the iPod preferences, music on the iPod can be played back through the Mac (or PC). This feature seems to be missing on the iPhone, according to Newswireless.net on Tuesday.

The author noted two changes in the operation of the iPod functionality of the iPhone.

"If you want to load the new albums ..., you’ll have to create a playlist in iTunes first and then sync it with your iPhone. If you later decide you want to remove one of those albums from the device, you’ll have to remove it from the iTunes playlist and sync again.... This is precisely the kind of tortured user interface that the overly smug Mac Guy lampoons in Apple’s ubiquitous advertisements," Dan Goodin wrote.

Second, an even worse, "this change means it’s impossible to plug an iPhone into a computer and play its contents through iTunes....The iPod pictured has manual music management enabled. When it is connected to a computer, its songs appear in iTunes in black, meaning tunes can be clicked on and played.

"Compare that with the iPhone. There is no way to enable manual management. As a result, entries in the music library are gray, designating there is no way for iTunes to play them [through the computer.]," the author lamented.

This deficiency of the iPhone was seen as severe and cripples an important social aspect of the iPod functionality: "The iPod’s ability to play music through a computer allows users to come together and play new tunes for friends in a way that is perfectly legal and highly contagious."

The author pointed out that Apple claims that the iPhone is the "best iPod we’ve ever created." However, that missing feature could lead to undesireable tinkering and hacking by customers.

iPO has verified this non-feature, but observes that Apple does things for a reason. In this case, it may be related to iPhone security requirements. Reader comments and the iPO forums may clear up this subtlety of iPhone operation.