ICBMs are great and all, but since they are used almost exclusively for nuclear strikes, launching one would practically guarantee WWIII. So, to get non-nuclear ordnance anywhere in the world in under an hour, DARPA is developing the reusable, hypersonic Falcon delivery system.
The Falcon (Force Application and Launch from CONtinental United States) Project is a joint venture between DARPA and the US Air Force as part of the military's Prompt Global Strike initiative aimed to deliver missile strikes anywhere on the planet in under 60 minutes. The system comprises two parts: a launch vehicle, and a hypersonic glider.
DARPA currently uses the X-41 Common Aero Vehicle (CAV) as the Falcon launch vehicle. The USAF already uses the X-41 for many of its ICBMs as it can reach speeds of 13,000 mph—that's fast enough to get from London to Sydney in 49 minutes. That means many targets would be accessible in a half an hour or less.
The Falcon glider is a sub-orbital, wedge-shaped delivery module launched from the X-41. It's constructed from an array of exotic materials like carbon-carbon, which is used for both the body and aeroshell which provides protection against the extreme temperatures that moving at Mach 20 produces. These parts are built (or rather molded and cured) from piles of polymer composite using a recently unveiled "tape-wrap" process. This fabrication technique drastically cuts the cost of producing these vehicles. This technique requires 10 times fewer parts, 50 percent less human labor, and reduces the production cost by 40 percent per pound of carbon-carbon.
DARPA has already attempted two test flights—in 2010 and 2011—aimed at collecting detailed flight and telemetry data, though both missions failed about nine minutes into their planned 30-minute flights. If this technology does ever come to fruition, the US military hopes to use the same launcher technology to put small satellites in orbit. [Wikipedia 1, 2 - Wright-Patterson Air Force Base - Parabolicar - Space 1, 2 - Image: USAF]