It's been a while, but I just published episode 24 <http://bit.ly/dBrRIm> of RadiantCasts. You'll see how to use and configure the Comments Extension, to add blog-like comment functionality to Radiant. (external link<http://blip.tv/file/4337498> http://blip.tv/file/4337498 )
Comments, suggestions? Thanks, Cristi