Actually, this article about Continuous Integration, has been posted only in french. Indeed, I think there is so few document about it in french (and so plenty of it in english), that I have decided to write one.
Nevertheless, I have a definition and some very good materials in english for you here : an article from JavaWorld and three good presentations.
Continuous Integration (CI) enables automated builds of your project on a regular interval, ensuring that conflicts are detected earlier in a project’s release life cycle, rather than close to a release. More than just nightly builds, continuous integration can enable a better development culture where team members can make smaller, iterative changes that can more easily support concurrent development processes. As such, continuous integration is a key element of effective collaboration.
The article “Introducing continuous integration” on JavaWorld.