It seems that both Creech AFB as well as Area 51 in Nevada are active as ever, with various new projects, including newer generations of UAVs as well as UCAVs, in addition to possible newer hypersonic spy planes.
Here is a post (December 23, 2009) found on the net:
MORE MYSTERIOUS BOOMS IN SAN DIEGO
It happened again. An earthquake hit San Diego, but Scripps Institute later said it wasn't the earth shaking, it was a "compression wave originating one hundred miles off the coast."
I have been living on the coast here for thirty years, between North Island Naval Air Station and Miramar, and I have heard dozens of sonic booms.
This was no sonic boom.
Fire Departments here evacuated engines, 911 was deluged with calls, it was far more dramatic, lasted much longer, and felt very different than a sonic boom.
The same damn thing happened a couple years ago.
Both times the military stated that they had no operations at the time, and they had no idea. Scripps said they had no idea what it was...could this be a flying vehicle nobody knows about, travelling at a "hyper velocity" to Nevada from the Pacific?
Here is the newspaper article on the San Diego mysterious boom:
Here is another recent news item out of Nevada: OUT OF NEVADA COMES 'BEAST' ---- Area 51 and Creech AFB
Also, Northrop Grummans seems to have this on its drawing board, a possible follow-up to B-2 BOMBER
NORTHROP GRUMMAN SECRET BOMBER PROTOTYPE: