HA! From the article: "The pace of software development is accelerating. Agile processes, application frameworks, and cloud deployment platforms are force-multipliers driving this change. The PostgreSQL project has seen these trends and is embracing them."
Hstore (the key/value data storage Heroku is introducing) has been available for postgres since before 8.1, circa 2005.
...and Postgres comes packaged with OS X. Lovely.
What version is it, does it have support for hstore? If not...homebrew ftw!
Last time I looked it came with 8.4; I would highly recommend installing 9.1. A lot of awesome things have come out in the last few years.