How do you handle source control setup of a project that has dependency on a separate framework or library? For example, Project A uses Framework B. Should Project A also include the code from Framework B in its repository? Is there a way for it to be included automatically from a different repository or would I have to updated it manually? What are the general approaches are usually taken for this scenario? Assume that I control the repositories for both Project A and Framework B and that the source code for both is not compiled.

Any resources or suggestions would be greatly appreciated. I'm currently using Subversion (on a very basic level), but I would like to switch to Mercurial so that I can try out Kiln with Fogbugz.

Edit: In Mercurial, would you use parent repositories for this function?