QUOTE: The worst part was differences with dates and the pickyness of postgres with joins
Urgh. The ANSI standard very clearly states that if you mix implicit and explicit joins, the explicit joins go first. So, this query:
select * from a,b join c on (a.id=c.id)
won't work in any compliant database, because a.id doesn't exist yet when joining b to c. And guess what happened in MySQL v5.1? That type of join started throwing an error just like pgsql does.