It's been steadily eroded after a couple hundred years of court cases. It's really depressing to see almost all our constitutional rights now gone by this same process. When the government can explain their right to kill citizens extra-judicially in 16 pages, something's gone wrong.
I think we need a second bill of rights which re-establishes our rights in detail (and updates them for the digital age) and explicitly voids all contradicting precedence. That should last us another 200 years.
Specifically to your point, from what I know, surveillance is ok in public places. These drones clearly violate that since they could be watching your backyard BBQ. Worse, they could peer through skylights, into courtyards, through your sunroof, etc. But I'm sure the wise judges will find another reason based on precedent that this is ok.
...anyone?