I know it's possible to deploy earlier versions of the .NET framework using AD deployment, for example: http://msdn.microsoft.com/en-us/library/cc160717.aspx.
How do it do this for .NET 4? I tried unpacking the standalone .NET 4 installer and deploying the netfx_Extended_x86.msi package. This didn't work. After a reboot the event log shows that it tried but it failed to install with a message saying to run setup.exe.