Since Mr. Dalai Felinton have been working on a build with 3D stereoscopy that would soon be implemented into blender, I thought I would make something of a relation. With this node Tree, you simply have to render the two views (and thanks to Mr. Felinton you only have to render it once), connect them to their corresponding inputs, and the rest is history! No need for extra work :D
To use this node tree, all you have to do is to first append the node tree from the 3D.blend file to your file, input the left and right images (whether it was an image or a render output) and connect the output format to the compositer, or to the output node in the case of 2 formats as mentioned in the .blend file.
P.S. the glasses in the picture is not included in the blend file. It is there simply to demonstrate the 3D effect achievable.
P.P.S. The two formats mentioned before only work with 1920x1080 images currently. I will update that soon if I remember :P UPDATE! forget this c:
ANOTHER UPDATE! I added instructions on how to use this file :D
nice.. sir.