I don't think it's going to be practical this century. The difficulty is that the same properties that let you cut the latency are the ones that make the detectors huge: Neutrinos go right through the Earth, and also right through your detector. There's really no way around this short of building the detector from unobtainium, because neutrinos interact only through the weak force, and there's a reason it's called 'weak'. The probability of a neutrino interacting with any given five meters of your detector material is really tiny, so you need a lot of them, or a huge and very dense detector, or both. Then, you can't modulate the beam; it's not an electromagnetic wave, there's no frequency or amplitude. (Well, to be strictly accurate, there is, in that neutrinos are quantum particles and therefore of course are also waves, as it were. But the relevant wavelength is so small that it's not useful; you can't build an antenna for it. For engineering purposes you really cannot model it as anything but a burst of particles, which has intensity but not amplitude.) So you're limited to Morse code or similar. Hence you lose in bandwidth what you gain in latency. Additionally, neutrinos are hard to produce in any numbers at a precise moment. You're relying on muon decays, which of course are a fundamentally random process. So the variables you're actually controlling are the direction and intensity of your muon beam, and at respectable fractions of lightspeed you just can't turn them around on a dime. Plus you get the occasional magnet quench or whatnot, and lose the beam and have to spend five minutes building it up again. So, not only are you limited to dots and dashes, you can't even generate them fast and reliably.
All that said, what application other than finance really needs better latency than you get by going at lightspeed through orbit? And while it's true that people would make money off that, I don't see any particular social return to it. Liquidity is a fine thing, but I cannot fathom that it matters to have it on millisecond scales - seconds should be just fine, and we're already way beyond that just with lightspeed the long way around. As for blackout zones, are you thinking of cellphones? I suggest that this is a bad idea. To get a reliable signal in a man-portable detector you would have to have a very intense neutrino burst indeed; and then you'd also get a reliable signal in the body of the guy holding it. We detect neutrinos by the secondary radiation they cause. I haven't worked the numbers, but even if cancers were rare enough to put up with, think of the lawsuits.
Wait wait wait. A muon beam exists? How does that work? How accurate is it? Does it only shoot out muons, or does it also shoot out other particles?
In response to falenas108's "Ask an X" thread. I have a PhD in experimental particle physics; I'm currently working as a postdoc at the University of Cincinnati. Ask me anything, as the saying goes.
This is an experiment. There's nothing I like better than talking about what I do; but I usually find that even quite well-informed people don't know enough to ask questions sufficiently specific that I can answer any better than the next guy. What goes through most people's heads when they hear "particle physics" is, judging by experience, string theory. Well, I dunno nuffin' about string theory - at least not any more than the average layman who has read Brian Greene's book. (Admittedly, neither do string theorists.) I'm equally ignorant about quantum gravity, dark energy, quantum computing, and the Higgs boson - in other words, the big theory stuff that shows up in popular-science articles. For that sort of thing you want a theorist, and not just any theorist at that, but one who works specifically on that problem. On the other hand I'm reasonably well informed about production, decay, and mixing of the charm quark and charmed mesons, but who has heard of that? (Well, now you have.) I know a little about CP violation, a bit about detectors, something about reconstructing and simulating events, a fair amount about how we extract signal from background, and quite a lot about fitting distributions in multiple dimensions.