Since September 11th, we have flown twice. Oakland to Phoenix (and return) and Oakland to Salt Lake City (and return). At all three places they required us to show our e-ticket confirmations not only upon check-in but also at the security check point and with Southwest also at the gate. I would play it safe and have it readily available to show anyone who asks for it. The situations at airports still seem to very very fluid and changeable. Better to play it safe and be prepared for anything.