I think a lot of people / services do something along these lines. Not sure if you saw this, but Netflix recently came out with a very nice blog regarding load shedding.
A lot of people had outages today, most of them unavoidable, but for us, many of our services were slow to come back. It got me thinking about load shedding and how to avoid the thundering herd when things are coming back online. Does any body else employ this strategy? Is there a better way to think about this?