There is a sea change coming, at least in some subset of the user-aware development community. As of now people are examining the computer and computer software finally through the lens of "how confusing is this to the user?"
I don't know if everyone remembers, but the personal computer was only the first step in an inexorable journey to the internet and more recently the social web.
Every one of the realizations that are currently hitting the hardware and software markets of personal computing will hit the internet and social network markets as well, in a year or two max.
Twitter is about as popular as it's going to get, it's way too user-unfriendly. Heck, even facebook is a pain to use.
We are going to see the rise of insanely intuitive social networks in the near future, and if nobody pays any attention to users and interfaces that are actually useful Apple will be one of the few (if not the sole) attendees of that party as well.