Hi guys,
I'm Philipp, web developer from germany. I invested a lot of research into package managers, dependency tools, build tools and deploy tools to get projects, focused on the backend (like php websites) to fluently work with frontend code (like js libraries, or frontend packages like bootstrap). Unfortnately I came to the same conclusion jordi came up in april 2012 (!). So the situation is not changed, yet.
Within my little research I found a lot discussions about the different package managers in the js community. They just can settle on anything. In a result of all this, everyone is building his own solution which isn't wide adopted. The jQuery project is starting to use its own package.json manifest file, bower has a really horrible registry (which is maintained by a single github issue), component(1) is forcing everyone to use common js modules, npm is to limited to node (and not browser libraries or modules). It's just getting worse over time.
I think the idea is really really great, but It will be very complicated to start the discussion.