Starting with the Q1 2010 release we’ll be building against .NET 3.5 SP1. This is a new requirement and older releases are still compatible with .NET 3.5 RTM. There is no change in the requirements for the .NET 2.0 builds. Generally speaking, there is no reason why you shouldn’t install .NET 3.5 SP1 on your servers and workstations since this is the current official version of the framework.
The reason for this requirement is that we’ll start shipping official .NET 4.0 builds of RadControls for ASP.NET AJAX when VS 2010/.NET 4 RTM comes out. The service pack is a prerequisite for using the 4.0 tool chain. In order to avoid changing the system requirements shortly after the release, we’re making the change now and notify you about it in advance.
We hope this won’t cause you any hassles.