So we have modules, plugins, rather recently extensions, and now—expansions. Is there any development info on them? Is the MSM a one-of-a-kind add-on that onle EllisLab could pull off, or would it be possible for third-party developers to develop their own? does it need support in the EE core code? (I suppose so.)
In a word, what makes an expansion unique, how does it differ from, say, a module? Any more info would be greatly appreciated.