[Haskell-cafe] Questions for Free!

Hello Haskellers, So I have a bit of a follow up question after reading Theorems For Free! this weekend. There's a throw away comment near the beginning about how you can recast the results into category theoretic form, but using lax natural transformations. Now I'm assuming this means a natural transformation but where the "naturality" square holds only up to isomorphism instead of equality, but is that correct? Also, why would you need such a condition? Cheers, Creighton