Just want to say this is a great topic and an article from which I learnt a lot. Perhaps it should feature more prominently.
Over recent weeks I've been struggling with understanding how it all hangs together grabbing snippets all over the place, reading through loads of the php source, slow & difficult progress.
I have no doubt it would have taken me several more days to workout that the 'task' was defaulting to display and that I could name my own controller methods (like jump) and have them activated by a URL parameter. (The sort of stuff I imagine every PHP developer coming to Joomla would want to know).
The article may also be a bit dated now with 1.7 I see the demo Hello World MVC component involves 4 files ?? (Basefile + M+V+C) ? Anyway, well done great article and lots of gems of knowledge about how Joomla works. Thanks