C# when developed is of version 1.0 (ECMA standardized). Later it is upgraded to 1.5 (ECMA standardized) and then to 2.0 (ECMA standardized) and now the current version is 3.0 (not yet standardized by ECMA). Though version 3.0 is not yet standardized by ECMA, Microsoft released the 4.0 version (Beta). So I reckon Microsoft is trying to add some more additional features to C# 3.0 as it a major release.