Here is an example of a GoL unit cell - "a pattern with two states, which is determined by its previous state and the previous state of its neighbors, using exactly the rules used to compute it; that is, it simulates its own universe": http://www.radicaleye.com/lifepage/patterns/unitcell/ucdesc....

Basically a pattern in GoL that mimics the behaviour of a single cell. A regular grid of these would therefore implement Conway's Game of Life in Conway's Game of Life (and of course you could do this recursively to any level you choose - at an exponential decrease in speed of course)