I just got home to find my Time Capsule's status LED flashing yellow. This is a story of two problems with the Time Capsule user interface.
If I read the Time Capsule manual at all, it was many months ago. I can't remember what ‘flashing yellow LED’ means, but given that it spends 99% of its time solid green, I figure green = good, and yellow = bad. I've been an Apple user for some four years now, so I'm with the program. Troubled by the LED's flashing yellowness, I fired up AirPort Utility. There was, in fact, no problem at all—there just happened to be a firmware update available. Firmware updated, Time Capsule reset, and the LED is now a comforting solid green. This strikes me as an awful way to signal the availability of new firmware. Surely this could be integrated into the system-wide Software Update facility.
In any case, the hilarity did not end there. Time Machine was running a backup during the update, but the Time Capsule apparently made no attempt to terminate that gracefully. While the Time Capsule rebooted after the update, Time Machine displayed an error dialog, and the backup failed. For a piece of hardware that's sold specifically to work with a piece of software, this complete lack of integration is disappointing.