Stocks of the iPod nano appear to be dwindling at retailers across the country, suggesting that Apple is planning to update the tiny music player soon. 9to5Mac spotted shortages at Amazon, Target, Walmart, and Best Buy—a common indicator that a product is about to be refreshed by Apple.

The sixth-generation iPod nano was released in 2010, a radical departure from previous nanos. Not much larger than the iPod shuffle, the sixth-gen nano is dominated by a small square touchscreen with limited multitouch abilities. Though it includes an iOS-like interface, it still runs the same Pixo OS that powered previous nanos as well as the iPod classic.

Apple didn't bother updating the nano (or really, any iPods) in 2011 aside from a slight price drop and a few software changes, such as the addition of a Nike+ fitness app. But the short supply of the current nano suggests Apple may have something more in store this year.

Where exactly Apple could go with the nano, though, isn't clear. Apple embraced the small "watchband" industry that sprung up around the sixth-gen nano by adding several user-selectable "watch faces" for the built-in clock. A source for iLounge has suggested that Apple may extend the smart watch concept further by adding low-power Bluetooth 4.0, enabling a nano to connect to an iOS device like an iPhone running iOS 6.

"The feature would enable a future iPod nano to display iMessages received by an iPhone, record voice memos that could be shared via the iPhone, and even initiate phone calls through its own headphones," according to iLounge's source.

Bluetooth 4.0 would also extend the iPod nano's fitness tracking capabilities, allowing it to connect to a wide range of sensors and monitors, like cadence sensors for bicycles or heart rate monitors used to track cardio fitness.

Another possibility is the addition of camera hardware. The fifth-generation iPod nano model included an inexpensive video camera, so it wouldn't be entirely surprising for Apple to include something similar in a newer, updated nano. A leaked prototype suggests Apple has already experimented with this idea as well.

The video feature of the previous nano doesn't appear to have been all that popular—Apple did, after all, see fit to exclude it from the sixth-gen device. However, we think if the company does add a camera, it will probably include still image capture, even if it's low resolution. As some photographers are wont to say, the best camera is the one you have with you, and we think a camera feature could be a hit with younger kids. (Anecdotally, the iPod nano's video camera seemed to be a hit among the kids of Ars staffers; there was a bit of a crisis once the camera disappeared from the latest model.)

Considering the nano's small size and $129 starting price, though, don't expect anything better than what the iPod touch currently includes. There's simply no room for the kind of high-quality camera module included in the iPhone, but something like the 6.5 × 6.5 × 3.3mm module could probably just fit in a nano.

Finally, Apple may end up opening the iPod nano to developers. As we noted, it doesn't currently run iOS (even though it looks like it does), so developers may not be able to easily port over existing apps. But it does use a processor similar to the early iPod touch, so perhaps Apple could shoehorn in a cut-down version of iOS just for the nano—at least, enough for developers to get creative. Or Apple may offer an iPod nano-specific SDK as it did in the past for developing games for older iPods. Either way, we suspect that letting third-party developers extend the device could make it more appealing to a wider variety of users.

Apple is expected to hold a media event on September 12 to announce a new iPhone, and it's likely that any iPod announcements for the year would also happen at that time. What would Apple have to announce to make the iPod nano a compelling product for you? Let us know in the comments.