I've been both in panel interview and on the panel for interviews. It really isn't that much different from a regular interview. Except you have more people that will ask you things from many different angles. I wouldn't even bother finding out the positions of each interviewer since most likely there will be one from every position. However, a few positions that you can expect to be on a panel are the people who will be: your immediate boss, co-worker that is holding the same or similar position that you're applying for, may be an HR person (unless that was the person who called you), and probably a few more people who happens to be free on that day
. My only advice is be prepared for everything, and never act like you know something that you don't. Also, review your past projects that you described in your resume to make sure that you remember all the details. It is very likely that you will be asked about that.
Usually if they used up all the allocated time for the interview that is a good news.
Good luck.