A hypersonic spy plane, often called the “Aurora,” has been rumored to exist for more than a decade. So far there has been no official confirmation.
You can read more about it here.
This video features photos that could well be that aircraft.
Here’s a couple of images of a plastic model kit based on “the technical requirements of hypersonic aircract … to develop a reasonable guess as to what [Aurora] might look like.”
They do bear more than a passing resemblance to the photos featured in the video.
Update June 21, 2009: Could these also be pictures of the Aurora?