open source = Open for public to help building. take Linux for example. It's free, because a lot of people work on it (developers), they do this voluntary.
Open source is a type of software that is free to use unlike licensed software. Cloud computing is where servers store data away from the physical computer. Combining the two means that cloud computing open source is free software to store your data remotely.
There is a website called OpenStack.org, where you can find the cloud computing open source. At the website you can meet the community and you can access to other projects.
Wikipedia has a good section on open source cloud computing to help you get started. OpenOffice.org, Google Documents, StarOffice and many others offer various open resource cloud computing products.
pervasive computing
Yes, Google Docs is an open source solution to your problem. With Google Docs you can store your files online.
An open system is a system that allows a great deal of flexibility. Similar to open source software, it allows users to improve the work as time goes by.
The R Project for Statistical Computing is a project that involves a free and open-source environment for statistics and graphing. It runs on a variety of different platforms, including UNIX and Windows.
The term Screem is mostly used for computing language with various development softwares. The term refers to the open source editor of HTML and a XML for UNIX based systems.
Yes, Google, Oracle and Amazon.com also offer cloud computing solutions. Many companies also choose to build their own from open source resources. Wikipedia has some useful suggestions and information on cloud computing.
Open source operating systems can trace their ancestry to many trends in computing of the 60s and 70s. If one had to put a face on the concept, it would be Richard Stallman. Stallman formed the Free Software foundation, and developed or commissioned many of the necessary components of a free and open-source operating system. Note that Stallman doesn't like the term "open-source", since the source can be available but still restricted in what you are allowed to do with it.
VNC Virtual Network Computing
The short answer: Open source dev paradigm