On Monday, I blogged about a mysterious sonic boom heard in San Diego (and made gentle -- OK, not-so-gentle) fun at UFO proponents about it). No one knows the cause of these booms, though it's safe to say an alien ship is pretty low on the list.
A followup story has been published in the same newspaper that had the first article about this. Scientists have traced the origin of the noise offshore, to a section of the Pacific known to have "military training exercises". That's a logical place to continue looking for the source, of course.
However, even if it does explain the noises heard in San Diego, it does not account for similar booms heard over other states in early April. So there's still more to this story. Stay Tuned.