Office automation has been existence for many years, but often in the form of VBA scripts or Macros. This type of development required a very specialized set of skills and was typically difficult to support.
Today Office 2007 and 2010 support a robust set of interfaces that can be created with any standard Visual Studio .NET toolkit. Combine this with Windows Workflow Services and document content types in SharePoint, and you have a powerful automation tool for custom document generation, review, and publishing.