About fifteen years ago (!!!) Mark Weiser proposed that the aim of design in an age of ubiquitous computing ought to be to create "calm technology."
As Weiser and John Seely Brown put it in a 1996 article [pdf],
The most potentially interesting, challenging, and profound change implied by the ubiquitous computing era is a focus on calm. If computers are everywhere they better stay out of the way, and that means designing them so that the people being shared by the computers remain serene and in control. Calmness is a new challenge that UC brings to computing... Computers for personal use have focused on the excitement of interaction. But when computers are all around, so that we want to compute while doing something else and have more time to be more fully human, we must radically rethink the goals, context and technology of the computer and all the other technology crowding into our lives. Calmness is a fundamental challenge for all technological design of the next fifty years....
Information technology is more often the enemy of calm. Pagers, cellphones, news-services, the World-Wide-Web, email, TV, and radio bombard us frenetically. Can we really look to technology itself for a solution? But some technology does lead to true calm and comfort. There is no less technology involved in a comfortable pair of shoes, in a fine writing pen, or in delivering the New York Times on a Sunday morning, than in a home PC. Why is one often enraging, the others frequently encalming? We believe the difference is in how they engage our attention. Calm technology engages both the center and the periphery of our attention, and in fact moves back and forth between the two.
In order to evaluate the degree of calmness, we first need to define the characteristics of calmness in a ubiquitous application.... According to the dictionary , 'calm' means "free from agitation, excitement, or disturbance." Therefore, disturbing is opposite to calm. Weiser & Brown  state that calm technology is a new approach to fitting ubiquitous computing to our lives. Weiser defined a ubiquitous system as calm in his visionary paper , although he did not use the term 'calm.' Instead, he stated that "computers will be used unconsciously to accomplish everyday tasks."
This isn't a problem of computer scientists failing to pay attention to a large literature on calmness. So far as I can tell, there's no philosophical literature on calmness-- it's neither a property that is a subject of sustained philosophical inquiry (like contendedness or happiness), nor is it one that has been dissected and analyzed (the way, say, the terms "language" and "mind" have been). But I don't think that definition goes far enough. It's appropriate for everyday use, perhaps, but we're talking about something different in the computational and device context.
Weiser and Brown, I think it's safe to say, defined "calm" in much the same way Riekki et al do: as being "free from agitation, excitement, or disturbance." In other words, calmness is the absence of distraction or excitement; it's a kind of neutral ground state that people naturally return to when they're not being bothered by things, and which we seek to recover.
Another sense of "calm" is a physiological or physical state. Waters are calm when they're not being churned by wind and tide; likewise, people are calm when their muscles are relaxed, heart rates and blood pressure are low, and adrenaline and cortisol levels are normal. Calm is equivalent to your resting state.
Neither of these are inaccurate, but I think when talking about "calm technology" they're insufficient. What Weiser and Brown were really getting at is a kind of relationship between devices and users that may be "calm," but is anything but natural. Rather, it's a kind of calm that emerges out of deliberate practice, an intimate knowledge of craft and tools, and is an expression of self-control.
Think of the literary trope of monk-like assassin (Hideo in Gibson's Neuromancer or Konrad in All Tomorrow's Parties, George Clooney's character in The American, Max von Sydow's Joubert in Three Days of the Condor). Their calm isn't a function of pathology, but a sign that they're masters of themselves, their craft and weapons; their calm makes them efficient and implacable, unhurried, and utterly confident.
Likewise, there's a long tradition linking warfare and spirituality. The samurai are a famous example, but you can find such connections in virtually every culture and age.
Here's the thing: they're not in these fields because they're calm people. Rather, their deliberate, meditative attitudes are the product of years of training.
People who do incredibly challenging things under tremendous pressure, and remain calm while doing so, usually attribute their success to the excellence of their training, and the richness of their previous experience, not to innate qualities.
In other words, this is a kind of calmness that is not inherent in technology (the Quantas crew that landed the damaged A380 wasn't flying an unusually calm plane), nor is it just a physiological state: it's a form of highly-trained engagement.
Finally, the long history of contemplative practices argues against the "calmness as default" model. The first thing people learn about meditation is, it's damn hard: it requires a strange kind of intensity and focus. Buddhist writers talk about the mind as like a monkey, always distracted by one thing or another, and it can take years to learn to meditate effectively.
So my argument is that that kind of calmness that Weiser and Brown were describing, and that ubiquitous computing researchers have tried to create (or have argued against), isn't the product of great design, or simplicity; and it certainly is not achieved, as Yvonne Rogers' criticism [pdf] suggested, by anticipating the needs of users and doing things for them.
Rather, calmness with technology arises out of an intimate familiarity, out of practiced and often varied use.
Philosopher Alva Noe, in his excellent and challenging book Action in Perception, argues that "perceiving is a way of acting," the result of "skillful visual probing" rather than a passive-- or even just highly edited and filtered-- but largely automatic activity. Seeing, Noe might it, is not a default activity: "You enact your perceptual content, through the activity of skillful looking."
Likewise, calmness with technology is not defined by the absence of stimulation: it is an active form of engagement that requires training and discipline, and a deep understanding of both devices and self.
I think such an approach to calmness can help us clarify our thinking about calm computing, and about what the design aims of ubiquitous computing ought to be.