Sahil , on his new blog , is on a tear writing quite a few detailed nuts-and-bolts articles on ASP.NET 2.0 Web Part development with focus on MOSS 2007:
» ASP.NET 2.0 WebPart Communication: The Preface to Sharepoint 2007 WebPart communication » Writing Custom Webparts for Sharepoint 2007 » Sharepoint 2007 WebParts Communication » Writing custom editors for Sharepoint 2007 and ASP.NET 2.0 WebParts » Sharepoint 2007 WebPart Connections - The Theory before the Code