Not for 'proper' production (still missing a few libraries and C++/swig related stuff), but I have a collection of scripts that I use all the time that reads in data from various sources, does stuff to that data and then writes out that data to new files. Typing "pypy foo.py" instead of "python foo.py" gives me a 3-7 times speed up without having to make any changes to the source code. Can't really argue with that.
Quora ran PyPy briefly before switching to Scala in production, see: <a href="http://www.quora.com/Alex-Gaynor/Posts/Quora-is-now-running-on-PyPy" rel="nofollow">http://www.quora.com/Alex-Gaynor/Posts/Quora-is-now-running-...</a>
My coworkers and I use it instead of C Python for practically every script we use in our bioinformatics research. It works seamlessly, but "research scripts" are probably a perfect niche market for pypy.
Mike Tigas made a PyPy buildpack for Heroku:<p><a href="http://github.com/mtigas/heroku-buildpack-pypy/" rel="nofollow">http://github.com/mtigas/heroku-buildpack-pypy/</a><p>Here's his blog post about it:<p><a href="http://v3.mike.tig.as/blog/2012/02/13/pypy-on-heroku/" rel="nofollow">http://v3.mike.tig.as/blog/2012/02/13/pypy-on-heroku/</a><p>I haven't used it on a serious project yet, but it was pretty easy to work with.
Check out seatgeek, I know they're using it in production. I think they do most of their string analysis with it when they are scraping other sites to collect ticket data