Defining Intelligent Services
Intelligent services, from businesses to governments, all need software in order to analyze the intelligence they gather. Intelligence software is, thus, the software that they use. Such software is essential to develop any sort of sense of what is going on in today's chaotic world and to wade through the onslaught of digitized data and come to usable conclusions. Historically, intelligence software has been dominated by proprietary software suites. However, this has begun to change as more and more intelligent services switch to using open source products.
Be careful not to confuse this with similar terms. Open source intelligence may also refer to the information that can be gathered from publicly available locations, for instance newspapers or books. This is a very traditional form of intelligence gathering used by governments and businesses alike, a method that can be compared to more covert acts of espionage and the like. In this usage, it is referred to by the acronym OSINT, as defined by the US Office of Management and Budget.
Some people also use the term to refer to projects that attempt to gather knowledge in the public domain for public use, Wikipedia being a good example of this. However, this use is somewhat less common.
Obviously open source intelligence software may take advantage of open source intelligence methods, but it's important to remember the distinction and to clarify where necessary.