I've got two games using this same 'framework' which is just a shared object file that I'm putting common OpenGL functionality in.

Anyway, I'm trying to set up a good lighting system here:

//Gl is a namespace BTW
            Gl.glEnable(Gl.GL_LIGHT0);
            Gl.glLightfv(Gl.GL_LIGHT0, Gl.GL_AMBIENT, new float[] { 1.0f, 1.0f, 1.0f, 1.0f });
            Gl.glLightfv(Gl.GL_LIGHT0, Gl.GL_DIFFUSE, new float[] { 1.0f, 1.0f, 1.0f });
            Gl.glMaterialfv(Gl.GL_FRONT, Gl.GL_AMBIENT, new float[] { 0.5f, 0.5f, 0.5f, 0.0f });
            Gl.glLightModelfv(Gl.GL_LIGHT_MODEL_AMBIENT, new float[] { 0.5f, 0.5f, 0.5f, 0.0f });

Both games have virtually identical classes|objects at the start of the game (introduction and main menu, etc) but in one game, the texture and all of the glColor3f seems to be overridden because all of the colours are greyish - but the other game is fine.

Firstly, is there any basic attributes that I'm misconfiguring or not configuring in the code above?

Secondly, what could override all of the glColor functions to produce all-grey results?

Nah, light simply affects the colours but it doesn't make everything the colour of the nearest light or anything. If you project a green light on a green object, that object would look fine but if you project the same light on a purely red object, it should turn black - this is assuming that you're using diffuse lighting though. But that's the general idea.

Are you certain? If I set glMaterial to 0,0,0 , wont I get black? And if I set it to 1,1,1 wont I get white in that case? Which parameter(s) should I be configuring?

What does get me the most is that it does fine with the other game, which has almost the same code up until past the main menu...

Ah yes, now I understand.

slaps forehead quite hard

I just realised that the texture is actually grey in colour and that the colours came from the glColor parameter - I was hoping of animating the title a little, and the menu selection is just a change in the glColor parameters.

But it's good to know that glMaterial would fix this up.

But that way he won't learn anything... ;_;

Yes, but the right way to deal with lighting is to learn to use the material properties, not to hack around it with GL_COLOR_MATERIAL.

Yes! I are smart!

Not necessarily.
If you want your rendering code to render the model correctly both with and without lighting, GL_COLOR_MATERIAL is actually a choice that makes sense. The object rendering code doesn't need to know whether lighting is enabled, it just sets the color through glColor() and all other properties through glMaterial().
Though in practice, your objects would typically all be lit at all times.