Updated Time Capsule opened, server-grade hard drive nowhere to be found?

Well, fancy that -- a teardown of last week's refreshed Time Capsule has revealed a regular, non-enterprise drive lurking within. Curious, as Cupertino's website lists a "Serial ATA server-grade hard disk" as standard equipment on the device's official spec sheet. It's generally assumed that for a drive model to be qualified as "enterprise," it must sustain a mean time between failure -- MTBF for short -- in excess of one million hours. So what's the MTBF for the Western Digital's WD20EARS (Caviar Green) in HardMac's Time Capsule? Conveniently, the hard drive maker wouldn't say. Of course, we guess the definition here is up for interpretation, but given past experiences with the wireless backup gizmo, we'd certainly hope this improved revision fares better.