In 1991 Mark Weiser wrote the article: "The Computer for the 21st Century" presenting the visions for future computing that he and his colleagues at Xerox PARC worked at.
Weiser states that the greatest technologies are the ones that are not noticed anymore. They are constantly present in the background, but do not call for attention. They are ready with the information we need when we need it.
Weiser advocates for a different approach to thinking about computing, one that takes natural human environment into account. The focus should be the task at hand - not the technology.
When people are very familar with a technology then they do not notice it anymore according to Weiser. He makes references to Georg Gadamer and Martin Heideggers notion of "horisont" as an equivalence to concept that the person ceases to be aware of his knowledge when something is learned sufficiently well.
Weiser also labels ubiquitous computing "embodied virtuality" - which is the process of "unleashing" computers in physical space. This is opposite to "virtual reality" that aims at re-creating the world within the virtual world.
In embodied virtuality it is very important that the ubiquitous computers know where they are and that the right scale is chosen.
The location awareness ensures that the technology can fairly easily adapt to the environment. The scale gives different possibilities. In the 90ties they worked with Tads, Pads and Yards (the former is smallest, the latter biggest). The strength of the concept is not the devices in themselves but what emerges from the interaction between them.
Finally ubiquitous computing aim at focus at the task and the "people in the other end" more than on the tool.
Weiser is mainly dealing with computing for workspace whereas I am interested in using the technology in an entertainment setting.
As Weisers' - and his colleagues' - ideas are the beginning of ubiquitous computing and thereby pervasive computing it makes out the basic idea behind pervasive gaming.
WEISER, Mark "The Computer for the 20st Century", 1991, Scientific American, pp. 933-940