I've never seen it taken advantage of in any of the Sci-fi books I've read or TV shows or movies I've seen...
With faster than light travel, combined with adequate sensors or telescopes, nothing that happens in public--ever--is private or a mystery.
Want to see what happened during that battle 2 days ago? Fly your ship 2 light-days away, turn around and with a telescope you can simply watch it happen in real time.
I suppose that does cut through all the discover-what-happened mystery plot devices and is why it's not used in Star Trek, etc. But still could be a cool bit for a book :)