We've received reports from several Apple Stores across the US stating that some AirPort devices are either low in stock or out of stock altogether.
A reader let us know that all of the Apple Stores in his area are out of AirPort Express models, and one of our sources confirmed the Apple Store in his area is out of stock on not just the Express, but the AirPort Extreme and Time Capsule as well. Another source says supplies at one store are not constrained and never have been, but the store "may have" received a notice to send its AirPort device inventory back.
We've heard nothing in the tech grapevine about upcoming refreshes to the AirPort line of products, but generally when Apple's inventory channels get constrained like this, it's a good sign a product update is imminent. It's worth noting that this year's WWDC is widely expected to be a software-only event, so if the AirPort line is indeed being updated, it's unlikely we'll hear about any upgrades then... unless Apple plans on somehow tying an updated AirPort line in with its iCloud offering. Shared data running off of local storage like a Pogoplug? Could happen.
Of course, Apple doesn't have to unveil any such hardware updates at a conference, and if the updates are going to be nothing more than modest feature bumps, they may just appear out of the ether the next time the Apple Store goes down.
Apple's online store still offers "within 24 hours" shipping times for all of its AirPort products, and not every Apple Store we've contacted has been able to confirm device shortages. However, it has been nearly two years since the last upgrade to the AirPort line, so it might be due for an update.