Rendering RGB normal map

How would I render a 3d object as a RGB normal map?

object space or tangent space?

onto a lower detail mesh?

nvidia’s melody or “open render bump”
[there are other tools, but those I’ve used before]

My question is not specific enough. I’m looking for a python plugin that will give me an rgb normal map of an object I have modelled in blender. I remember a plugin that gave z-depth information in shades of grey. The RGB and RGB normal are combined in a 2d game to give the impression of depth.

http://www.blender.org/cms/Normal_Maps.491.0.html

should have looked a little harder.

I hate the new forum search feature.