...aaandddd... here it is! A semi-working effect-file shadow mapping implementation!
As you can see it's not perfect yet (for some reason, the pyramid doesn't have any diffuse lighting even though it's facing the light) but wow - I'm so pleased! I am really looking foward to seeing how this performs in my main game project at the moment!
EDIT: I figured out the diffuse problem - I was passing the wrong light location into the shader.