We tried the activity with great success in the retro that Jaggu was running; as did Rohith Rajagopal/ Siva Jagadeesan in the other retro that was running at the same time and apparently Pat Sarnacke tried this out in an end of release retro as well. So it looks like my friends have taken to my invention quite happily.
Coming to the activity; this constitutes dividing your whiteboard/ flipchart into 3 sections as the picture illustrates. The section on the left (illustrated by a book) signifies Learnings; the section on the right (illustrated by the delta) indicate things that the team will do differently and lastly the section at the bottom (illustrated by the cross) which indicates items that the team wishes to avoid. Pat phrased the purpose of each of these sections a little differently for the end of release retro that he was running. The rest of the format is pretty similar to other retros - brainstorm on stickies, group them, vote and decide on actions.
What I really liked about this activity was the fact that this very easily brought out action items for the team that they could carry forward to their next task at hand. I can easily see this as a roll off retro, an end of training retro, an end of release retro and I am guessing this could be an effective one to run when time is short and yet we wish to come out with tangible/ practical outputs from the time alloted to the retro.
If you decide to run this activity for your next retro and need help, please feel free to email me and ask and I'll be happy to assist. Do let me know your experiences with this cuz I'm eager to hear about them.