Rumors are floating around that SQL Server 2008 could be RTM'd as early as July 31!!! That's right, the product team has hinted at an August release time frame (thanks to Francois Ajenstat).
This release will align with the soon-to be-RTM SP1 for .NET 3.5 and Visual Studio 2008, which has hooks into the new features of SQL Server 2008. SQL Server 2008's installer now also requires that the .NET 3.5 SP1 be installed, and will attempt to download it as part of installation process.
If you're trying to install the RC0 rev of SQL Server 2008, you will be asked to install the beta SP1 for .NET 3.5 first.
NOTE TO VISUAL STUDIO 2008 USERS:
If you installed the hotfixes for the Web Designer in VS 2008, which were recently shortly after the IDE was released, YOU WILL HAVE TO UNINSTALL THE HOTFIXES prior to intalling SP1.
These hotfixes were rolled up into SP1, and will cause the beta installer to fail if you've already got them. The installation log actually details the KB articles related to those hotfixes.
Once you've removed these hotfixes, the SP1 installer will finish up without a hitch, and you can move on with the setup for SQL Server 2008 (note to self: blog about the new installer experience of SQL Server).