A Delta Airlines app is on the way
www.tuaw.com/2010/08/06/a-delta-airlines-app-is-on-the-way
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Just the other day, a Delta executive mentioned in a short interview that a Delta iPhone app is on the horizon. It's not clear yet what kinds of services and features the app will provide, though it's a safe bet the American Airlines app will give you a decent guess.