UPDATE: There was an issue with the originally posted download regarding the Batch Site Manager and Permission Reporting tools, this has been fixed. If you experienced a problem, simply uninstall, re-download the package, and reinstall.

I'm not going to cross-post, but check out the announcement over on the team blog:
   http://blogs.msdn.com/sharepoint/archive/2009/08/27/announcing-the-fourth-release-of-the-microsoft-sharepoint-administration-toolkit.aspx

I do want to make a special callout that the Permission Reporting Tool (check effective permissions, etc) requires that you be running at least the April 2009 CU for WSSv3.  You can be past this, but that is the first release that contained the check effective permissions API that the tool utilizes, so for that tool it is required.  If you are just going to use SPDiagv2, etc, you don't need to be on the April 2009 CU for WSSv3 or later.  Only the Permissions Reporting Tool carries that requirement.

Enjoy!