MSDN RampUp - SharePoint for Developers and mssharepointdeveloper.com
Both these sites have articles, webcasts and hands-on labs designed to help .NET developers to learn the key points of SharePoint development. A variety of materials with different learning styles help you get started doing SharePoint 2007 development.
The Great SharePoint Adventure - WSS 3.0 and MOSS 2007 for Developers
If you want more than the quick boost provided by the resources above, you can get a broader and deeper picture by taking our five-day course. It's about 70% instructor demos and labs and you get to take all the code back to the office with you for reference.