I only hope it won't be too long before various "drivers" and frameworks start supporting it, otherwise the acceptance rate will be too low. And Jsonb deserves to be accepted as fast as possible.
That's how it was done for 9.3's expanded diagnostics[0], and as a result both Python's psygopg2[1] and Ruby's ruby-pg[2] (and maybe others) added extended diagnostics support before 9.3 was even released[3], and working from day 1.
[0] http://www.depesz.com/2013/03/07/waiting-for-9-3-provide-dat...
[1] http://psycopg.lighthouseapp.com/projects/62710/tickets/149
[2] https://bitbucket.org/ged/ruby-pg/issue/161/add-support-for-...
The excellent slick-pg library which extends the FRM library slick. https://github.com/tminglei/slick-pg
https://docs.djangoproject.com/en/dev/ref/models/custom-look...
https://docs.djangoproject.com/en/dev/ref/models/custom-look...