The answer to the previous question was: "it does work". I don't know how the framework I'm working on exactly works, but it does strange things with depth buffer.
It seems I'm at a good point. Shadow mapping consists in three steps (two, if the video cards supports the GL_ARB_shadow_ambient extension):
- depth buffer acquisition from light's point of view
- a "dim light" rendering from camera's point of view
- full light rendering w/ shadow map depths comparison
New question is: why doesn't the shadow map show up..? ^^"