Well I know that there are implantable devices that relay vital signs back to monitoring equipment to show heart rate etc. This was very useful for astronauts and divers, but also from a military perspective it would be good to identify if your troops are still alive, and be able to identify them via satellite. It is only a short step to combine implantable devices with microphones that can relay information directly.
The only downside is that these people are never likely to draw a pension - which unfortunately is the most cost effective use of people.
We are seeing this in the UK military where less and less are serving long enough to draw a pension, or are let go a year or so before retirement. The combination of food, drugs, military hardware and chemical agent training may lead to a shortened life expectancy which, ultimately, saves on government spending.
Like most tools these days, they may be smarter but they are not made to last, and you just have to replace them more often.