Really fast

Keith Wagstaff has a Time article about hypersonic flight:

Fly anywhere on Earth in an hour. That’s the goal for the Defense Advanced Research Projects Agency (DARPA), according to Nextgov.com. DARPA is the Department of Defense’s secretive research arm known mostly for commissioning freaky robots.
How fast do you have to travel to reach any point on the globe in sixty minutes? Mach 20, or twenty times the speed of sound, in something called extreme hypersonic flight. To put that in context, Lockheed’s SR-71 Blackbird, the world’s fastest air-breathing piloted aircraft, maxes out at about Mach 3.2.
Making the jump to Mach 20 won’t be easy. According to DARPA, flying that fast would create temperatures of 3,500 degrees Fahrenheit, hotter than a blast furnace capable of melting steel. Not to mention compensating for things like wind gusts is difficult when you’re traveling at around thirteen thousand miles per hour.
A hypersonic aircraft would be used for “missions ranging from  space access to survivable, time-critical transport to conventional prompt global strike”. In case you were wondering, “prompt global strike” is military-speak for being able to blow something up anywhere in the world at a moment’s notice.
To reach its goal of launching a successful test flight by 2016, DARPA is hosting a Proposers’ Day on 14 August to reveal exactly what it’s looking for from companies that want to compete for about forty million dollars in initial prize money and thirty million dollars in renewal contracts.
Mind you, no one is expected to build this thing on their own, just develop technologies that will help it fly— like, say, skin that doesn’t peel off and cause the aircraft to crash into the ocean, as in the case of the Falcon Hypersonic Test Vehicle 2.

Rico says if they can pull it off, that'll seem cheap...