Mark Weiser described a hypothetical world in which humans and computers were seamlessly united in a seminal article a decade ago; he called this vision Ubiquitous Computing (which now is also called Pervasive Computing). After that, technology has advanced along many dimensions, especially in hardware progress and wireless communication technologies. A number of leading technological organisations are exploring Pervasive Computing. But it is far from Weiser's vision become reality. Pervasive Computing will be the future. Pervasive computing will be a fertile source of challenging research problems in computer systems for many years to come. But until today, there is less attention to the system evolution in pervasive computing environment. This paper discusses the current development of Pervasive Computing and technical challenges in deploying Pervasive Computing systems. First, a model for evolution of pervasive Information technology infrastructure of pervasive information is presented which shows how the existing technologies solutions available can be used to develop a pervasive information infrastructure. Then a generic architecture of pervasive computing system is given. Based these, an evolutionary system design approach is suggested.