A lot of meter-hate here.
Somoene said that the measuring is pointless because the power companies alreayd know how much power they send out. Actually that's not true any more. Only about half the wind generation in the UK is measured as 'grid input' - the rest is attached on the 'distibution side' of the main meters so it just gets used locally. Same for all the PV on roofs. This lot is a non-triivial fraction of generation, at least some of the time.
Smart meters may be expensive but you are all ignoring the costs of _not_ having them. That will be either blackouts or even more expensive supply. The ability to have much more flexible tariffs, some stuff which gets turned off sometimes, loaning your EV battery to the grid for balancing purposes and so on, is necessary to make a low-carbon grid work.
If you don't think you want a low-carbon grid then that won't impress you much, but again the costs of not doing that (knackered climate, food shortages, probably outright war after a while) are likely to be orders of magnitude more than 12 billion.
Yes, there are serious issues of control (who has it) and encryption (you can't actually read your own data from the meter except via the provider), but those are implementation details. The fundamental infrastructure upgrade is necessary. I just hope it's been designed right so we don't have to do it all again in 10 years time...
And these things usually send their data back over the GSM network. Some will use the power network itself, or other arrangements in very remote areas.
For anyone that cares the specs are here: http://www.decc.gov.uk/en/content/cms/consultations/cons_smip/
Rolling these out without the 'remote disable' feature would be one way of enormously increasing acceptance. People are right to be nervous about that aspect (as Prof Anderson points out).
Oh and on 'what use is real metering'. Well I found out that our 2 PIRs use 16W each all day on the offchance that someone walked up - that's not worth £40/yr so they got switched off. And I found a bell-transformer using 15W permenanetly despite the bell having been removed years ago, and a radio using another 11. There are probably millions of little power-wastages like this going on up and down the country. It's true that they won't help if you couldn't care less, but if you do care (even if only about the money, rather than the waste) then some data can really help you reduce your consumption. Most people who care, find that they can easily reduce consumption by 40%. Fitted to the houses of the populace at large (who mostly don't care) you get about a 4% reduction (that californian data). Our consumption dropped by about 30% and I thought I'd done as much efficiency as I could already.