The link: SharePoint 2010 Reference: Software Development Kit

MS has released a new version of the SharePoint 2010 SDK. It contains new code samples, updated IntelliSense XML files, and updated documentation based on customer feedback.

What's New in the SDK for SharePoint Foundation 2010

What's New in the SDK for SharePoint Server 2010

A full list of code samples can be found on MSDN Code Gallery.

In the future, MS will release new versions every quarter. That’s good news :-)

Hint:

In order to install the new release, you’ve to uninstall a previously installed SDK. If you don’t, the SDK will not install.