The number was 240. There is a thread about it in the Majors forum. Here's the email I got from airline apps.

"Delta will begin hiring pilots after the summer schedule ramps down in late August. Right now they anticipate needing an additional 240 pilots based on forecasted retirements and an increase in flying.

For those pilots interested in joining the Delta team, please update your application in the Airline Apps system. For those who don't currently have a Delta application in Airline Apps, simply add Delta to your job targeting or click the new applicant link to start a new application."