As far as I recall, there's Summer of Code project dedicated to getting Quanta4 going. Basically, most of the things that quanta3 did can now be implemented as some sort of chrome on the kdevplatform (the framework that also backs the recently released new version of KDevelop). http://milianw.de/blog/gsoc-revive-quanta-brand-for-kde-4 has more details about that. Milian is also the guy who has implemented pretty awesome support for PHP in kdevelop, by the way.

That's a misconception. Plasmoids can both be installed through your system's package manager (just like basic plasmoids that make up the desktop interface are), and starting with 4.2 also through webservices (Those of course only works for non-compiled language plasmoids such as Javascript, Python and Ruby). A security mechanism for installing them through webservices is in place. It'll probably also be possible to share plasmoids among users, to just drag+drop them from a webpage onto your desktop, panel or sidebars. The system is quite flexible.