Microsoft patterns and practices have released a guide: Developing Applications for SharePoint 2010
Each section also contains a set of how-to topics. These explain how to perform specific tasks that the team found challenging to discover.
This release includes eight reference implementations that you can deploy to a SharePoint 2010 test environment. The reference implementations reinforce the key concepts in the guide and illustrate how to build applications that reflect real-world scenarios. Each reference implementation includes a detailed scenario and design overview, an explanation of the design decisions the team faced for the implementation, and an installation script to automate setup. This release includes reference implementations for the following scenarios: