An AirPort Utility update released yesterday has been discovered to contain references to forthcoming next-gen AirPort hardware. MacRumors and 9to5 Mac have independently confirmed that the software update contains references to a fourth-generation Time Capsule and a fifth-generation AirPort Extreme.
Two weeks ago, we reported that stocks of Apple's AirPort products were starting to dwindle at Apple's brick-and-mortar retail stores, and over last weekend shipping times for the Time Capsule extended to as much as two weeks in several of Apple's international online stores. Many of us expected to see updated Time Capsules at WWDC, with potential ties to Apple's new iCloud service; although the hardware updates failed to materialize last week, the data in the latest AirPort Utility update is just one more piece of evidence suggesting that product updates are imminent.
The AirPort Utility update also contains references to software updates being stored on the devices, but MacRumors stresses that this is not a new development: "the same text has been found in older versions of the software dating back to at least 2010." It's possible this is a feature Apple has been waiting to implement until iCloud's launch or a Time Capsule/AirPort Extreme redesign based around an A4 or A5 processor.
At this time, we'd advise that you hold off on purchasing a Time Capsule or AirPort Extreme unless you absolutely, positively must purchase within the next few weeks.