Yes, as Ksanti says. They are using extension tubes and/or cropping. This lens is so sharp that heavily cropping isn't a problem.
I looked at the 65mm MP-E but it's very specialist, I don't think I'm that in to shooting tiny insects to give up how versatile the 100mm L is. It's much more a versatile lens. It's essentially a fast 100mm image stabilised prime, with a minimum focus distance of 30cm.
It's so refreshing to not be limited by the minimum focus distance. I'm going to really enjoy this lens. I've already planned where I'm going at the weekend to stretch its legs.