You can browse the SDK online through the following links:

· Office SharePoint Server 2007 SDK

· Windows SharePoint Services 3.0 SDK

For a full breakdown of what is new check out the SharePoint Team blog:

http://blogs.msdn.com/sharepoint/archive/2007/08/22/just-published-major-update-to-the-moss-and-wss-downloadable-sdks-8-22-2007.aspx