In this InfoQ exclusive article Trent Swanson provides an overview of Microsoft Office SharePoint 2007 and its architecture. In SharePoint, developers can use RPC which provides a more robust object model than web services however it does not support remote operations. This is where web services must be utilized to support remote operations and gain interoperablity capabilities.
A solid understanding of IIS and ASP.NET is important when developing any SharePoint based solution. Trent provides examples that walk through both .NET and Java in this introductory article on working with SharePoint web services.
