good results for displacement baking in 2.5

Can anyone post a few step guide to baking displacement in Blender 2.5?

I understand the concept behind displacement mapping and generating displacement maps, but I am unable to actually generate one. I always end up with a uniform grey image. I’m willing to bet that I have just messed up on one of the steps.

Any help is appreciated.

thanks

http://wiki.blender.org/index.php/Doc:Manual/Textures/Maps/Bump_and_Normal_Maps

http://blenderartists.org/forum/showthread.php?t=138194

There are tons more all over youtube as well.