The first publicly available technical preview of SQL Server 2008 R2 has just been released to TechNet / MSDN subscribers. As with the development of SQL Server 2008 each successive CTP will have more features in.
This CTP’s main feature is the Report Builder 3, and also included multiple machine management and support for 256 cores (which need Windows Server 2008 R2 as well).
So no Gemini preview this time around, which is partly due to the dependency on Office 2010 which hasn’t yet been made the subject of a beta as yet.
I haven’t seen this beta on our internal shares so I will be downloading really soon to see whether what has happened to Report Builder myself!