How about detecting devices? I never thought that SR4 was all that clear in just what a hacker finds and how much they know when they do a scan.
So for example, lets say a ganger goon is dumb enough to have a grenade in his backpack with the wireless on. How does a hacker even know it's there to hack?
Also, worrying about enemy hackers doesn't seem to me like it should be as big a worry as many make it out to be. The setting basically provided an excuse for all the script kiddies disappearing, the need for security spiders decreasing thanks to GOD taking the role, and the cost of buying/building a deck. Running into a Decker or TM (who actually decides to learn to hack systems and not just use the matrix as a normal person) shouldn't be nearly so common anymore. Sounds like commlinks with higher device ratings should be able to handle the Deckers and TMs from groups like gangs, small companies, low level security, etc. And if you're running into a group that has cause for a higher level hacker, then you should be on a level of gear, karma, and preparation to deal with them, unless there has been some very bad decision making happening in your team. Course, I'm basing this entirely off what I've read in these discussions since I haven't gotten my hands on the book yet.