Upgrade Content IT Pros may not have seen
Given the upgrade of WSS and MOSS may contain some customizations, IT Pros that are looking through TechNet may miss some great content that's actually in the SDK, something Server Admins don't usually think about cracking. The SDK has a lot of relevant content for IT Pros, so don't dismiss it.
Here's the key content I wanted to expose you to on this topic from the WSS 3.0 SDK.
Upgrade Overview
Site Versioning and Upgrade
Architectural Approaches to Upgrade
Using the Object Model to Upgrade
Sample Outline for Upgrade Actions
Upgrade Definition Files
Upgrade Definition Schema
Upgrading Pages and Web Parts
Other MSDN Content on Upgrade:
Migration and Upgrade Information for SharePoint Developers (tons of resources)
SharePoint Server 2007 SDK
WSS 3.0 SDK