I'd suggest opening bugs on drivers (that's the most important one) right now since the feature is officially in the development version. If it doesn't already work that is.

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-...

[3] http://www.postgresql.org/about/news/1481/