Distributed Computing
Wikipedia defines distributed computing as dealing with "hardware and software systems containing more than one processing element or storage element, concurrent processes, or multiple programs, running under a loosely or tightly coupled regime"
So defined, distributed computing is ubiquitous today: from the commercial world - where Google run web queries distributed over thousands of processors, and Amazon offer storage and computational services to remote users - to academia, where the LHC Computing Grid distributes particle physics data from CERN for analysis around to the world, and where scientists in many disciplines (e.g. astronomy, biomedicine, geosciences,...) integrate distributed data resources located worldwide.
While the technologies may differ in detail, as do the buzzwords used to market them - e.g. "Grid computing", "cloud computing", "computing on demand" - all approaches face a set of problems common to computing in a distributed environment. One of the goals of the MSc programme is to help students gain an appreciation of the generic issues, as well as providing hands-on experience of a number of the technologies which offer solutions to them.
Read more about the Research Councils UK e-Science Programme for academic applications and the Grid Computing Now! website for examples from the commercial world.