Michael Stephan Fuchs's 2006 novel The Manuscript is just what a technothriller should be: taut, violent, smart, and very, very technical. There's plenty of "technothrillers" where the two key elements -- weapons and computers -- are treated as magic stage-props, able to do anything (or be confounded by anything) that moves the plot along. They're written by writers who confuse "programmers" with "network administrators" and think that 200 years from now, "mainframes" will be important and sexy (rather than ancient and useless).
In The Manuscript, an enormous cast of characters comprising many sysadmins, many gun-freaks, several combat veterans, spooks from a number of agencies, named and unnamed, ten zillion cops, a group of murderous avenging Taoists, and Sir Richard Francis Burton and a group of Andean holy men who have discovered the secret of the universe.
Fuchs does a remarkable job of staying within the confines of what technology actually does (both the guns and the computers) while still putting together an immensely entertaining book filled with likable, bloodthirtsy people doing incredible things while the whole world is on the line.
It's everything a technothriller should be. I don't care much about guns, but I do know an awful lot about computers. Fuchs manages to make the gun geeking every bit as interesting as the computer geeking, which is the definitive sign of really good geeking. Hell, he even makes the philosophy geeking as interesting as the computers (he's got a graduate degree in philosophy and Big Questions are the Maltese Falcon of this book).
Though the technology is out of date (the story revolves around shenanigans on Usenet's alt.* hierarchy), The Manuscript packs several kinds of punch -- it's as if The Da Vinci Code had been written by someone who wasn't an idiot.