There’s now a literate Haskell version of the polyomino generator in the darcs repository (oh, yeah…there’s now a darcs repository). It’s written as a module that exports a single function, rank, that generates all the polyominoes of rank n. For values of n greater than 9, this can take quite a while…

darcs get http://www.codepoetics.com/repos/code to grab it.

This is a preliminary to a full-blown polyomino puzzle solver.