Google: Pineapple Plant Propagation (Excuse the alliteration :P) ... RHS has written all about it in various books.
If you get one from an organic food store with the leaves still on top (bottom...technically ;P) you should be able to propagate it, however a lot of places like to remove the leaves of spray the fruit with something to prevent rooting occurring.
Pineapples don't produce seed so don't try buy any lol!
Only one pineapple per plant tho
... It's a Bromeliad so it will produce "pups" at some point, generally after flowering.