Can I write GLSL just how I can write Cg shaders in Unity3d? Meaning can I write my game's shaders in GLSL, and then cross-compile to different platforms? Please respond ASAP. Thank you.

Anyone? Please.

1. This is the Lounge. I'm not sure your thread is in the right place.
2. Yes, but it isn't recommended because it'll only work on platforms that support it. See http://docs.unity3d.com/Documentation/Components/SL-GLSLShaderPrograms.html
3. The above link was literally the first link retrieved by the Google query "glsl Unity3D." Did you forget that Google exists? ;)