I believe that small blogs and RSS/ATOM are a good answer here. I can't and don't want to follow high-volume streams, be it Twitter or "news" blogs. However, if you combine 20 interesting but low-volume blogs in your feed reader, you will always know when something interesting happened, without having to check all those sites by hand.
(Of course I also have high-volume sites in my feed reader, but that's more for "news" / skimming though, not for keeping in touch.)
Blogs are like an archipelago of privately owned islands. Twitter is a whole continent.
RSS and Atom allow for people to tell the people on the other islands about what they wrote but it's a one-way message. For an interaction to occur someone has to go over to the private island.
With blogs the entire process of publishing, reading and responding is privatized and fragmented.
Twitter is a centralized location that unites publishing, reading and interaction in one faux-public location. There is utility in these kinds of social networks. The issue is that they are not public places.
Twitter controls how the information is written and read. Twitter optimizes for their own private interests that have nothing to do with intelligent discourse. In the early days, Twitter was an open platform with a large number of competing clients. Early users and developers invented the core interactions that we see now see on Twitter. Hashtags and retweets were not invented by Twitter.
Twitter has since put their API on lock down. They alone have the right and ability to make clients. As a publicly traded company they're now required by law to create products that increase shareholder profits. The evolution of the platform is out of the hands of anyone but the managers of a private company.
I hope it doesn't come as a surprise that intelligent public discourse is not as profitable as the cheap and simple thrills that seem to be the core of social interactions on the Internet these days.
There were plenty of "non-techies" who used Google Reader before it shut down. And at least in my circles there are plenty of non-techies who say that they don't get the concept of twitter.
EDIT: Both, Twitter and RSS, have their own terms and concepts which need some kind of introduction for most, especially non-tech people. For Twitter its hashtag, TL, DM, etc for RSS its stuff like Feed, Reader, etc
How exactly? In the time it takes you to register an account on twitter.com you could as well register an account on wordpress.com and publish via RSS. The main difference is that longer content is possible, that you could find even easier/faster/whatever alternatives because its federated and that your communications are not dependent on the policies of a single private company - which for non-us-citizens like me is operating under foreign law, a law I don't know as well as the local one.
I don't watch much TV, but what little prime time TV I've seen recently, seems to pimp their twitter acct and semi-relevant hashtags constantly both intro and exit to the program and even believe it or not, during the program they pop hashtags on the screen. Only about 1/30th the population watches survivor so this is probably news to most HN readers.
One of the biggest things is that there is one, singular Twitter app. There are a million RSS readers, but it's difficult to know which one to get. And, of course, it's a reader, not a publisher - you need a separate app for that.
(Of course I also have high-volume sites in my feed reader, but that's more for "news" / skimming though, not for keeping in touch.)