It's the old Church-Turing thesis in a way; instead of using logic gates implemented with silicon transisters, they're using physical blocks and switches in minecraft. The principals are the same, just a different 'substrate'. DNA can be used as a computing substrate[1], and at a more macro level, the structure of cells[2]. The minecraft guys have a lot more in common with the early computer engineers who used relay switches and diodes on rotating drums.

[1] http://en.wikipedia.org/wiki/DNA_computing [2] http://en.wikipedia.org/wiki/P_system