Those who've been paying attention are likely not at all surprised, but it seems the federal government has been paying more attention to what American citizens do within American borders than they have been willing to admit.
Of course, there are questions about whether this is illegal (or even unreasonable), but I think it's rare to find an American who doesn't feel a little sick at the thought. There are many themes worthy of discussion (e.g., civil liberties), but I think it might also be useful to consider the nexus of technology, capacity, and control, and whether we implicitly "want" government to be less-than-effective, less-than-efficient.
In other words, there are many laws that Americans don't want perfectly enforced (e.g., speed limits). In the past, this has often been a pragmatic limitation, an acknowledgement that monitoring and enforcement were costly at most scales. But as invention (and mater familia "necessity") have made monitoring not only cheaper, but easier to scale, we see that "democratic" institutions are increasingly tempted by the power these technologies imply. And of course, the perpetual immanent threat to life and limb makes it much easier to allow liberty to fade into memory.
Are there any budding political theorists out there who are working on these themes? Surely, this would make a fascinating topic for dissertation research.