I'm using it in production, and speedups tend to be on the order of 4-5x for my app (the compute-intensive part involves hierarchical agglomerative clustering of documents by text similarity, so it's data/numbers-heavy). Obviously it'll depend on your individual application (and non-CPU-bound tasks won't benefit much), but we switched to PyPy because it showed major improvements in profiling of our app on production data (and we switched around PyPy's 1.9 release, so it's even better now). It's not like everyone's just imagining the speed improvements...