I have a cvs repository, with mostly java code. Each package sits in it\'s own top level dir, like so, with the sourced laid out in typical java fashion.
$CVSR
Regarding DVCS in general, a repo per component is the right size. Since they have the all history for their respective components, having only one repo for any component out there would not scale well.
Git will use submodules, Mercurial Hg will use subrepos.
The idea is to define a super-project (a repo in its own right) which will:
If you do some modification from the main project directly in one of those sub-components, you must first commit those subrepos, and then go up in your main project to commit that main project (it won't contains all the data, only its own data, and some pointer to the new submodules references you just committed before)