This is not a new or revolutionary idea. In fact, you probably do something close to this already. The problem is that "close" isn't good enough. Without compliance to some sort of formal specification, version numbers are essentially useless for dependency management. By giving a name and clear definition to the above ideas, it becomes easy to communicate your intentions to the users of your software. Once these intentions are clear, flexible (but not too flexible) dependency specifications can finally be made.
Version Control with Subversion
This is the online home of Version Control with Subversion, a free book about Subversion, a new version control system designed to supplant CVS.