Definitely be ready to talk about the projects you've led and be prepared to answer some key behavioral questions such as:
Tell me about the most difficult project you managed and how you overcame those difficulties.
Tell me about a time that you had a problem with one of your team members and how you handled it.
What do like the most about project management?
Make sure you are able to talk about project management intelligently and know the lingo. Know about:
the 5 stages of a project: initiation, planning, execution, control, and closing
the 4 stages of team building: forming, storming, norming, and performing
triple constraints on a project: scope, budget, and schedule
Know about the PMBOK and the bodies of knowledge that it talks about
Being able to prove you know project management and have had success managing projects related to what the interviewing company needs are the keys to getting the job.