That's exactly what I thought within 30 seconds of reading the artice, they already have a technology for dealing with outright server failure, why not have temp monitoring that gives a "virtual" fail and the existing redundancy picks up the slack.

The devil is probably in the detail however, in providing a graceful fail rather than an actual catastrophic hardware failure that user notice as a glitch in the matrix (eg. A search take 5ms longer than normal :-p)

In any case, it dosen't seem such an amazing revolutionary idea, but that's easy for me to say after the fact, and probably why I don't work for Google. :-)