Cosmonaut Keep (2001) - first in a 3 book series by Ken Macleod. The sequels are Dark Light (2001) and Engine City (2002.)

[Since I haven't read this - I'm quoting most of a review in LOCUS for a reasonable plot summary/set-up]:

"The galaxy of Cosmonaut Keep is dominated by abstract god-like hive minds, spacecraft piloted by enormous squid-like "kraken," and by long-lived "saurs" who dominate trade between worlds. For the most part, any humans to be found in this "Second Sphere" of interstellar culture are the distant descendants of alien abductees who travel between worlds on kraken-piloted vessels and trade on the good will of the saurs. The sole exception to this is the colony on the world of Mingulay.

Established two hundred years ago by a small group of Trotskyite rebels who piloted their way from Earth, the Mingulay colony is centered around the alien-built keep that they found there. Gregor Cairns, a descendant of the elite Cosmonaut Families, is more interested in his biological studies, though, than in interstellar history. However, when a trading vessel arrives from Nova Babylonia bearing a beautiful girl and the motivation to become involved in his family's Great Work - recovering the ability to navigate between the stars which was lost in the years following colonization - and establishing a trading fleet to compete with the kraken and saurs, that soon changes.

MacLeod interweaves the chapters set on Mingulay with a rising action set in 21st-century Europe. The conflict here is between a capitalist America and a communist Russia-dominated European Union lhat has absorbed part of the United Kingdom. In the Socialist Republic of Scotland, Matt Cairns works as a freelance software project manager and legacy system specialist, doing occasional pick-up jobs and struggling to get by. He is a character who almost seems, at times, to be a satirical take on the fictionalized disgruntled Soviet citizens who feature in so many Cold War thrillers. His girlfriend, Jadey, is a spy for corporate America. When, following the announcement that contact has been made with alien life out in the asteroid belt, Jadey shows up with plans for a flying saucer, things get pretty hairy. Matt is smuggled into the United States and, after helping to decrypt the plans, is placed on a stealth spacecraft headed for the research vessel that is working near the alien ship. On arrival, he finds himself caught up in a Trotskyite rebellion on board the research vessel, wondering why the ship described by the plans looks so exactly like a classic flying saucer.

While Cosmonaut Keep is clearly the first volume in a series, and doesn't attempt to answer the questions it raises, it is satisfying in itself, and shows MacLeod having a lot of fun. The chapters set on Earth are particularly engaging, with MacLeod coming on like some weird blend of Bruce Sterling and Billy Connolly, and his description of the future for the hacker community is both hilarious and oddly plausible. However, the world of Mingulay looks set to dominate any sequels. It should be an interesting ride." [-Jonathan Strahan, LOCUS April 2001]