Of plphp and plpgsql, plpgsql is by far the more mature of the two, having been written many years ago and thoroughly tested. And yes, it is almost an exact duplicate of Oracle's plsql language. More of a subset really, since I believe there are some minor features it may be missing that Oracle supports.
But you have to admit, the idea of being able to write your stored procs in php (there's a trusted and untrusted version I believe, which runs, of course, the non-safe and safe modes respectively) as well as the front end in the same language is quite appealing.
Mammoth pgsql is command prompts complete pgsql / replication package, all set up and ready to go. And while it costs money, it's a support contract, and there are no licensing limitations (i.e. number of servers or how you use them) put upon the user. pgsq.com has a similar setup.