I maintain QueueClassic (https://github.com/QueueClassic/queue_classic) for Rails/Ruby folks; which is basically what you're talking about - a queuing system for Postgres. A bonus reason, and why I originally wanted this was the ability to use transactions fully - i.e. I can start one, do some stuff, add a job in to the queue (to send an email), .....and either commit, or roll back - avoiding sending the email. If you use resque, I found sometimes either you can't see the record (still doing other stuff and it's not committed), or it's not there (rollback) - so either way you had to deal with it.

QC (and equivs) use the same db, and same connection, so same transaction. Saves quite a bit of cruft.