There's good news and bad news about the latest WinFX CTP for developers who want to use the new System.Speech API. The good news is that it is more complete and more stable than ever. The bad news is that there is still no support for attaching semantic values to a grammar to make it easier to extract the meaning of a spoken phrase once it has been recognized by the speech engine. I still get an exception whenever I attempt to use those constructs (see this excellent MSDN article for a semantics example), though we'll hopefully see them implemented in the near future.