Learn how to develop on Sharepoint by MSFT
If you are a beginner or experienced developer, Sharepoint can look pretty daunting at first...but it's ok because those clever people at microsoft have realised this and have put together a new mini-site which will help developers starting out in the world of Sharepoint and MOSS2007.
It explains what are and how to create web parts, workflows, event handlers page branding, web services and navigational along with quickstart code snippets, online virtual labs and much more... oh and C# and VB code (nice).
The site is very new and a lot of the content has not been finalised yet but hopefully by the time you read this there should be a lot more.
Check out the new site at http://www.microsoft.com/click/SharePointDeveloper/ ...oh and it's a way cool use of silverlight too!