The bump in the version number is to indicate DI/1 is moving closer and closer to a 1.0 release. 0.4.0 brings a number of bug fixes (handling of optional constructor arguments, addAlias() bug, circular dependencies in properties). I think DI/1 is pretty close to feature complete - at least as far as my intended usage as a ColdSpring replacement is concerned - but I will make one more pass over its functionality shortly and open tickets for anything that I believe is missing. Please feel free to do the same. Once that pass is complete, a 1.0 Alpha will be declared.