Southwest's schedule is now open through September 12. This extension occurred three to four weeks later than usual for this time of year. You can see just how bad our guesses were in the Official Schedule Extension Prediction Thread:
http://flyertalk.com/forum/showthread.php?t=527240
Ding also announces schedule extensions, so you do not have to wait for manual posting by me. Today's Ding announcement activated at 9:30 AM Central Time, about 15 minutes after the schedule was extended.
One other update: the initially tight capacity controls on new award tickets were apparently due to a programming error that was corrected in late February. Because there are still very few capacity-controlled awards competing for these seats, we do not yet have a clear picture of the eventual usability of these awards. Preliminary indications are encouraging, at least if your point of reference is saver awards on legacy carriers. It appears that if you avoid Fridays and Sundays to and from popular destinations availability will be adequate.
Oh, and the last major source of double credit, SWABIZ.com, dropped to single credit as of April 1. Too bad it's not an April Fool's joke.