It appears to me - based primarily on what I see on Stack Overflow rather than direct Mac use experience - that PostgreSQL packaging on Mac OS X is a real mess.
There are at least four widely-used competing package systems:
- An ancient version pre-installed in some Mac OS X versions
- Postgres.app from Heroku; and
- The EnterpriseDB One-Click installer for Pg
Fink and MacPorts packages also exist, but seem to have either fallen into disuse or "just work" so I don't see breakage reports about them.