Official NASA link
Audio from the first X43A launch, where the "plane" had to be destroyed
These photographs were shot from off-base (as you can tell by the poor quality) during the X43A test on March 27, 2004. The white item under the wing of the B52 is the Pegasus booster rocket. The X43A itself is probably too small to see. There are two F18 chase planes.
Check out the Edwards trunk radio page for talk groups specific to this exercise.