Fortune, what's the rationale on the WMI and why the RAS override isn't needed anymore?
I have to admit, a lot of that stuff is beyond me at the moment. I have only skimmed that chapter, but I'll give you a brief synopsys of what I know, and then you can either ask questions or read more on the subject at Dumpshock from people who truly do have a good grasp.
Basically, the WRI (or Wired Matrix Initiative), or Matrix 2.0, is all-pervasive in 2070 society. Think Minority Report on a wide, and sometimes even more invasive scale. The Commlink is the key to everything, being a combination cell phone, computer, camera, recorder, insert-anything-else-electronic-you-can-think-of. It contains your SIN information, and interacts with everything around it (like the retinal scans in Minority Report). You can 'hide' by turning your Commlink to 'hidden' (or even *gasp* 'off', but that attracts attention in certain areas. This is basically called Augmented Reality, or AR
Hackers (and Technomancers) can manipulate this AR, pretty much at will, with only a slight negative modifier to their real world actions. The closest analogy (and pretty much identical rules-wise in SR4) is to compare AR with Astral Perception.
The Astral Perception equivalent, and most familiar to SR3 players, is Virtual Reality, or VR. This is where the hacker 'leaves his body' and 'flies' through the electrons of the system.
Almost everything can be 'hacked' in SR4, including other people's Commlinks, and therefore everything hooked up to them (which is almost everything in 2070, including cyberware).
Anything and everything is 'tagged' with radio frequency 'tags', including clothes, guns. food, medicine, ammo, corp employees, etc, etc. Tags can be tracked! Of course, they can be destroyed, but they can be a nuicance at times, and a blessing at others.
