Lorenzo on IRC (nick: ciccio81) was looking for a high level diagram of QGIS for a university presentation on GIS and I realised we dont really have one! So I spent an hour or so knocking this together (open the image on its own for a non scaled version):

I tried using omnigraffle trial version on my MacBook to draw the diagram which got me about half way there before it said I had run over the limit of graphical objects allowed in the trial version and that I could not edit any further. Grrrr. Another reminder of why I like Open Source software although there isnt a really good diagramming tool that is open source that I know of. Luckily the GIMP came to the rescue for finishing the diagram off.

There are many other things I would have liked to add to the diagram but it would have made the diagram cluttered and I think what I have produced at least gives an at-a-glance overview of how QGIS is put together. Grrr I also just noticed there should be a green box for the Postgis provider...ah well maybe I'll make another version of the diagram sometime soon....