The trouble was that for more than a week I couldn't remember the "p" word -- my memory was turning into a forgettory, and I thought of "praeterist atonement" "praeternatural atonement", and "preeminent atonement" but the phrase penal substitution seemed to have slipped my mind entirely.
Then someone made a comment that triggered my rusty synapses, and I posted it on my Khanya blog here. It's an Orthodox theological response to the penal substitution theory of the atonement.
Then I thought I'd look on Technorati to see what others had been saying about it, and Technorati responded:
There are no posts in English tagged penal substitution”
So it seems that penal substitution didn't only slip out of my memory for a week or two, it slipped out of Technorati, and maybe out of the blogosphere generally, and maybe out of the universe!
Now there's a thought!