Apress’ Pro SharePoint Solution Development: Combining .NET, SharePoint and Office 2007, written by Ed Hild, Susie Adams is probably the first book I read that talks about Office Business Application, its patterns and how both the evolution on VSTO and OpenXML is used to develop Office 2007 solutions that fulfill various OBA pattern. So far I had downloaded Chapter 1 of the book and read a 100,000 feet overview on OBA patterns and various programmability of Office 2007.

OBA Pattern Categories
Office Applications as a Reach Channel :- Using Office to present data from other systems in an effort to simplify access or reduce duplication of effort

Document Integration:- Automating the generation of documents with data from another system or processing the documents to extract data

Composite User Interface :- Bringing together data from disparate resources into a single tool for the end user

Complementary Document Workflow:- Providing the ability to incorporate ad-hoc workflow into other line-of-business processes

Discovery Navigation:- Providing the ability to search and navigate through data of other systems

Collaborative Site:-  Using a SharePoint site to represent an instance of a
structured process

Application Generated Tasks and Notifications :- Consolidating task requests from systems into Microsoft Outlook

Link to A P R E S S . C O M : Pro SharePoint Solution Development: Combining .NET, SharePoint and Office 2007