I've been a developer, programmer, consultant, instructor, and consumer of personal computers and applications since the early days of CPM (pre-DOS). My early work started around January 1982 with the IBM PC on the connectivity and coding side, developing communications and custom business applications. Device-to-device communications was slow, commonly running at around 115 Kbps. I used to say I could make any computing device talk to any other computing device - just give me some cable, connectors, a few basic tools, an RS-232 Protocol Analyzer, breakout box, some paper clips to use as jumpers for cable configuration, and lots of Coca-Cola!
Times have changed - when I started almost 30 years ago, technicians typically drove commercial style vans full of tools and parts. Today a friend has a computer technology business where the technicians drive Mini Coopers. He's got one SUV to lug around bigger stuff but it does not see much road time. Times have really changed.
My current interest and technical focus is on connectivity (copper, optical and wireless), converged network (voice, video and data) services, end device hardware, operating systems and applications (that someone else has written!). Basically TCP/IP, Ethernet and everything involved in moving information securely, dependably and reliably from one device to another.
I still do take a thing or two apart these days though. Most recently I changed an iPod battery using a blow drier (to melt the glue holding device together) and guitar pick (get the thinnest picks you can find). Taking apart an iPad (why would anyone want to?) is not much different - here's a video from DirectFix.com showing how.
The days of vans full of technician tools, desktop type computers and field swappable components are either gone or rapidly going away. Some things do stay the same though - I'm still hooked on the Coca-Cola.