X51 is partially funded by DARPA (managed by AFRL) and sponsored by DDR&E and is REAL. The current highly efficient waverider configuration is fundamental to almost every airbreathing hypersonic platform proposed today.
The X51 program is, and always has been, a "national test bed" to provide 6 to 10 minutes of REAL hypersonic environment testing of any and all materials, subsystems and structure that needs be validated for most, if not all, of the current DoD and international platforms being proposed.
The difference is...X51 is very real , funded and being built. While many assume it is a missile based on it's shape, size and scale(economically sized for test demonstration that will validate scalability.... it will readily transition to MANY applications once it flies next year.
BUT... the demo vehicles will interrogate (in repeatable flight) the world's only fuel cooled 'reusable' hypersonic engine/propulsion technology in a series of envelope expansion flights. X51 has always been a demonstration of reusable fuel cooled propulsion technology to mature the path to low cost TSTO type space access .... something now identified as the economic paradigm to achieving SBSP (TRUE green energy for the world)and other economically viable commercial markets (including hypersonic transports of small to large scale).
Exciting? What could be more exciting than to know... this one is real and happening on plan... and it will make feasible many of the interesting artist renderings we see in articles like those above. Stay tuned.... metal chips are flying!