Charlie Stross has been hanging around the extropians email lists and it shows. His latest book, Accelerando, (like his earlier book Singularity Sky) is replete with matrioshka brains, characters who live out at least portions of their lives in simulations, people who fork their identities across multiple bodies or software agents and reintegrate the separated memory streams, planet terraforming, and AIs with undiscernible motivations. He weaves it all together into a rousing tale.
The apparent popularity of the novel (the short stories that comprise the sequential vignettes of Accelerando were nominated for quite a few awards) makes me think there's a chance that all the inside references and barely expanded concepts might be familiar enough to most SF readers. To me, it read as a novelization of the best years of the extropians list. All the things that people worried about and all the possible scenarios that people worked through in great detail are visible in at least passing views in the final fleshed-out forms they reached on the list. If the concepts he relies on aren't too SL4 for most readers, it should do quite well, because it's a fun read.
The first part ("Lobster", "Troubadour", and "Tourist") follows the adventures of the peripatetic Manfred Macx as he flits around the world economy, inventing wildly and giving away his patents to deserving charities, or whatever custodian will most piss off his various creditors. In later chapters, the various members of his household and its progeny scatter to the distant corners of the universe along with the rest of expansive humanity. Macx's is not a nuclear family in the conventional sense, so the splintered factions head off in many directions and several combinations, which enables them to be present as humanity and post-humanity inhabit near-earth space, explore farther out, begin turning most of the solar system into computronium, and become less and less recognizable. Necessarily, the story mostly follows characters who have opted to remain more or less human, though, as in Marc Stiegler's Gentle Seduction, the gradual changes accumulate rapidly.
The book is nominated for the Prometheus award, but any libertarianism it displays is subtle enough that some on the nominating committee, while admitting that it's a good read, have whether it deserves a place as a finalist. The book has an air of freedom, and I'd like to argue that, though the libertarianism isn't front-and-center, the book presents a society that works without any central government, and that shows its characters and political factions getting along without resorting to governmental force.
In the first three chapters, we see a fair amount of commerce and crime, and most of the enforcement is privatized, or limited to (threatened) court enforcement of contractual terms. The subplot in which Manfred frees the music is about changing the rules for ownership of property, which some may see as akin to theft, but it seems to me that it's a sensible exploration of alternative choices. If technology makes the old schemes unenforceable, ceding increasing amounts of force to the state (or to property owners) in order to maintain rights that have always been inventions of the state in any case (patent, copyright, trademark) is probably the wrong approach from a libertarian point of view.
Chapter 4 ("Halo", ") starts out with Manfred's daughter, Amber, escaping the clutches of her mother by emigrating to the asteroid belt. She ends up the head of a voluntary justice association that people subscribe to because it's better situated to their problems. The characters refer back to this period throughout the rest of the story, and it's clear that it serves as a reminder that voluntary arrangements work better.
The story ends with a transhuman superintelligence (the cat, Aineko) needing something from Manfred, and having to negotiate with him to get it. It's clear from the power arrangements that Aineko is used to manipulating events so people want to help her, but in this case, she needs a willing assistant, so she offers Manfred something he's wanted all along: to be left alone to live his own life. It seems plenty libertarian to me.