Um.. I think Hollowtech is a type of crankarm design and the octalink is the Shimano version of how the crank arm is connected to the bb. So they aren't related in that way. I'm pretty sure they make Octalink Hollowtech cranks.
For example, older XTR cranks are hollowtech design with an octalink interface and so are the black shimano 105 road cranks.