The new sdks for SharePoint have come available on 21^th of april.

Please download them and install them on your dev environments.

Sharepoint server sdk link

What's New in This Release for the Microsoft Office SharePoint Server SDK
The SDK 1.5 updates include a new version of the Microsoft Business Data Catalog Definition Editor tool (bug fixes for field truncation issues and parameter limits), and updated documentation page, What's New in the Office SharePoint Server 2007 SDK.

Wss3.0 sdk link

What's New in this SDK
Each update of the Windows SharePoint Services 3.0 SDK contains significant new conceptual, procedural, and reference material to help developers create customizations and applications for Windows SharePoint Services. In this release, you can find the following new and updated content:

• Expanded documentation of backup and restore features   This release contains greatly expanded documentation of backup and restore features, including a new top-level node, "Backing Up and Restoring." The node includes twelve articles, including "Overview of Backing Up and Restoring Data in Windows SharePoint Services," and four new How To topics.
• Complete documentation of Microsoft.SharePoint.Administration.Backup   Object model reference documentation in the Microsoft.SharePoint.Administration.Backup namespace is complete, and code samples are provided for all critical types and members.
• New documentation of the administrative object model   A new section, "The Administrative Object Model of Windows SharePoint Services 3.0," contains six new articles, and the "Administration" section has a new, extended code sample.
• Revised Web Part documentation   The section that provides conceptual documentation of Web Parts has been completely restructured, and two walkthrough topics have been significantly revised and rewritten.
• More migration support   A new section, "Selective Content Migration," contains three articles to support selective migration strategies. Additionally, additions and revisions have been made to existing topics in the "Content Migration Overview" section, and a large number of API reference topics that support migration and deployment scenarios have been completed in the SharePoint.Deployment namespace.
• Expanded and updated reference documentation   You can find enhanced documentation of types and members in the SharePoint.Workflow and SharePoint.WorkflowActions namespaces, the People Web service, and three ActiveX controls.