Last week, we released the Visual Studio 2008 SDK - July 2007 CTP targeting Beta 2. As James detailed on his blog, there were some rough edges if you were trying to get started with the new Visual Studio Shell.
In an effort to address these problems as quickly as possible, we've fixed the problems around VS Shell development and refreshed the SDK as the August 2007 CTP.
Note that the only changes between the July and August CTP's are the VS Shell fixes. All the other samples, tools, etc. are identical.