The nano is also not a “smart watch.” While it’s nice to have some music on your wrist and even some photos, the nano begs for an app architecture that would let third-party developers create new watch features, faces and other wrist apps. There’s also no connectivity. One can imagine a Bluetooth connection to the iPhone that would allow users to see messages, reject or take incoming calls and allow content (think weather updates and various push notifications) to be sent to the wrist for display.

Wearing an iPod on your wrist also requires some big shifts in habit. Unlike regular watches, the iPod nano needs to be re-charged every few days, depending on how much you use it as a music player. Apple not promoting the iPod nano as a watch right now, which is wise. But I do expect that it’s looking closely at how people are using this device, and taking notes for future product development.

Overall, the iPod Watch is an amazing concept. It shows the power that form and function have to create new experiences out of the familiar. I suspect that Steve Jobs’ mention of a member of Apple’s board being interested in wearing the iPod nano as a watch was less of an anecdote and more of a trial balloon. It wouldn’t shock me if a future iteration of the iPod nano was indeed entirely wrist based, with added integrative features and apps that makes it work more closely with other devices such as Apple TV or iPhone.

The world of invisible, wearable gadgets is going to be a vital part of mobile computing. It’s a shame to let such valuable property continue to go un-developed. Here’s hoping that Apple takes the time to invest and deliver on the long unfilled promise of wrist-based devices.