The 'chemputer' that could print out any drug. For implications, see "Rule 34". (Or 1998's "Holy Fire" by Bruce Sterling, for a look a little further down the line ... Bruce is always a decade ahead of the rest of the SF field.)
I'm pretty sure some of the British police forces are proactively engaging in internet monitoring already; here in Edinburgh they're already running anti-cyber-bullying campaigns in schools.
So far I haven't heard about any venture capital partnerships throwing the rule book out of the window and getting into organized crime business process re-engineering, but I may have been thinking too small.
So. Just as "Halting State" was basically at the "stick a fork in it, it's done" stage when Google announced project glass, I think we're creeping up on the finishing line for "Rule 34".
And in about a month I'll be getting down to work on "The Lambda Functionary", the third book in the trilogy, set circa 2030, in a world where the second and third generation descendants of ATHENA are in widespread use, the global population is ageing and greying (in particular, in Europe, where by 2030 the median age is projected to be 45.4).
What are your expectations for the world of 2030? (Singularities and catastrophic collapse of civilization scenarios excluded: I want "if this goes on ..." projections, not Book of Revelations schadenfreude.)