Airtran, Delta, Atlas, and Jetblue all plan to hire this summer/fall. It isn't a huge wave, but it is positive movement.
I would also suspect that there are a few UPS and FedEx guys that have employee numbers from DAL that might strongly consider going back if it were somehow possible. While air cargo has had a fantastic run, the last economic cycle showed more contraction in freight than in passenger business. The change in retirement age, the elimination of 3 pilot aircraft, overseas bases, and overall slow advancement for a mid 2000s hire might have some families having some interesting conversations around dinner tables. The "security" of the cargo business really evaporated for a lot guys the last 2 years..especially at UPS. It will get good again...but "good" is going to be a very long wait for some guys at the bottom of the lists.
I don't know when the cargo guys will open the hiring windows again, but I think there will always be someone who wants to fly for FedEx. For UPS, however, I think attracting anyone who could go somewhere else will be more difficult based on the rough handling they gave their guys 2008-2010. Money has a way of motivating folks, but I don't think anyone will ever look at a "stable, safe" company mantra the same again.