Singularity Sky is the first in the "Eschaton" books by Charles Stross. It introduces us to Martin Hannigan, a ship engineer on consultancy to an insular backwoods stellar empire known as the New Republic. It seems one of the New Republic worlds is under attack. It's not a naval attack, but rather an infovore-type society known as the Festival, dropping nanotech replicators and telephones onto a feudal society. Along the way he meets up with UN covert operative Rachel Mansour as they attempt to salvage what they can of the attack, learn about the Festival, and keep the New Republic from bringing down the wrath of the Eschaton on them thanks to the navy's attempt to use some time travel trickery.
I'll keep it short on this one; basically, I find it entertaining, and good for setting up some of the base concepts of the characters of Rachel and Martin, not to mention the universe. But on the whole, I like Iron Sunrise a lot more as it shows more of the universe in general, and not just the backwater part of it. The idea of what happens to a feudal society hit by the Singularity is interesting, but I almost feel like there could've been a lot more done with it than just the radical cyborg soviets. There's almost two books wanting to come out in here - one about Rachel and Martin and the thoroughly uninteresting New Republic (who never really feel like scary bad guys, or even particularly interesting ones at that) and Burya Rubenstein, the titular head of propoganda for the wannabe rebellion on Robard's World (the one invaded) and his dealings with everyone from the Critics to a mysterious boy leading a life of adventure.
Still, I'd suggest it, if only to read once so that Iron Sunrise makes more sense. On the other hand, I found that Iron Sunrise made plenty of sense without it, so take that as you may.