The MCSD title still exists, but you can't take the tests for it anymore and it's no longer really relevant. Starting with .NET 2.0, MS restructured everything into MCPD (Professional Developer) and MCTS (Technical Specialist).
For .NET 4 you want to be looking into MCPD. See here: http://www.microsoft.com/learning/en/us/certification/mcpd.aspx#vs2010. They've changed the structure a bit with every release of Visual Studio - I did my certs in the 2005 era and became an MCPD-EA (Enterprise Applications), which required you to take a base .NET framework "foundations" test, the MCTS tests for Windows, Web and Enterprise Applications, and then the Pro test for MCPD.
It looks like with 2010 they got rid of "Enterprise Apps" and went to Azure-related certification instead, and they restructured the requirements and made WCF and data-access specific tests.