Microsoft just released
Visual Studio 2008 and the .NET Framework 3.5.
.NET Framework 3.5
To develop applications for the .NET Framework 3.5, download
SharpDevelop 3.0 from the build server.
Note that SharpDevelop 3.0 are not release quality builds, especially the integrated
debugger is very unstable. As currently no one is working on the debugger (hint: you
can help!), I disabled it in SharpDevelop 126.96.36.19945 so that people trying SharpDevelop
3.0 do not immediately get exceptions when they try run their programs. To re-enable
the debugger, open C:\Program Files\SharpDevelop\3.0\AddIns\AddIns\Misc\Debugger\Debugger.AddIn.addin
in a text editor and remove the <DisableAddIn .../> node.
Read the complete post at http://laputa.sharpdevelop.net/NETFramework35Release.aspx