Microsoft's Pattern & Practices group has released a new, updated version of guidance for building collaborative SharePoint applications that extend your LOB systems.
This guidance helps architects and developers design and build applications that are both flexible and scalable and it focuses on four key areas:
- Using SharePoint capabilities to build more powerful applications;
- Building SharePoint applications that are easier to scale, maintain and grow;
- Improving application quality through testing;
- Improving and accelerating team productivity.
Check-it out these resources:
MSDN: Developing SharePoint Applications: http://msdn.microsoft.com/en-us/library/dd203468.aspx