The emergence of home networking and broadband internet access.
I've been building computers since 1996, and I can remember how much of a limitation it was that only one computer in our household could access the internet, as well as the fact that we had to have a second phoneline just for that purpose.
When I first was able to run a Sygate NAT'ing router on my main PC, and installed a 10Mbit hub and network cards in both our computers, that really changed the way we used computers in my house.
Compare that to today where networks are found everywhere, and hooking up to a wired or wireless network and getting broadband internet is just a no-brainer. We take the internet on our PC just for granted, since we are always connected 24x7. It didn't use to be like that for anybody but college students on campus networks or businesses.
Hell, even my phone (Pocket PC/Windows Mobile 2003 SE) is internet connected 24x7 with ISDN speeds. Its even a no brainer to drive out away from my apartment and hook my laptop up and wirelessly connect to the internet via my phone anywhere I go.
I think that is kind of the big change.